Any tangible or intangible advantage to shooting C41 B&W vs. color negative films and converting to B&W?

The only advantage I can think of is that you can say you shot it in B&W in the first place rather than it being a conversion (and you're the only one who would know anyway). I can't see any difference between C41 B&W's and converting to black and white after scanning it... and I've tried it.

Even decades ago, some people shot in colour film and then decided to make a black & white print of it in the darkroom. I tried it myself a few times in the 1970's. The chromogenics are very much like that... just colour film without the colour dyes. In fact, they aren't even really black and white. If you scan them, you still have to take the colour out of it.

Despite that, I still prefer to use Ilford XP2 when I know I want black and white. It's just a philosophical thing. I don't like the idea of converting anything from what it is to something else. I would rather use real B&W film, though.

BW400CN is going to be finer grained than Portra 400. Or any other 400 speed color film. It's a hair grainier than Ektar 100, and that's saying something. Take a look at the PGI numbers in the Kodak spec sheets.

On the other hand, you can do a lot of different B&W conversions in Photoshop from a color original. With a B&W film, you obviously have to filter in front of the film at the time of the photo. Personally, I don't use filters that much, nor do I really like doing B&W conversions, so when I want B&W, I shoot B&W.

You really have to see what you like. I never liked the c-41 black/white films while I knew others who thought they were great. I found it to be too flat and muddy for my tastes--at least that is how I remember it, but I also scanned it which should have equalized it, but didn't.

I gave up shooting black and white film quite awhile ago, mostly because I do scan my film. The control I have with color and digital post processing surpasses any control I had with b/w film, contrast filters in the field and development and darkroom manipulation. I generally decide when I shoot something if it is going to be presented in color or black/white, but sometimes I do change my mind--with color I can.

The new Portra 400 is pretty, dang fine-grained. It looks like 100 speed film to me. Very close to the Ilford XP2 I use to shoot with. I have not done a head-to-head against any C-41 B&W film and most likely won't. The upside of having both color and B&W options plus not having to deal with filters in the field, plus infinite conversion possibilities is too big an advantage for me.

Although actual print quality may be hard to distinguish, if you shoot color negative film you can work with the values of each color to gain the effect of using colored filters on black & white film. You can even use just one of the color channels (from RGB) if you like the effect. The late Monte Zucker used to split his digital images and sometimes keep just one channel for the final print. I think Shutterbug magazine did an article on this once. Anyway, you can do the same thing with a scanned color negative.

I think there is definitely some advantage of shooting color film and converting because you have some control over the filtration and contrast between colors, after the fact. For example you can use a red filter on B&W film, and get a contrasty sky. But with a color conversion, you can apply filters or adjust curves in a way that gives you more manageable control over contrast. For example, you could apply the equivalent of an orange/red filter if red is too much.

I'm quite surprised that no one seems to think that there's any decisive inherent advantage in shooting the C-41 B&W... Somehow, i can't quite accept the fact that a post conversion can be as qualitatively good as using the correct filters in the first place. I'm sure you are all correct, but it's still hard to believe for me without having had your experience in actually doing this, I suppose...

Monochrome conversions from color - whether film or digital - offer advantages in tweaking shades of gray for desired tonal separation.

Experiment with any of your own color photos. Convert one copy to simple gray scale. Split another to separate RGB channels (each should appear as monochrome). Note how colors are rendered as grays. The effect is particularly noticeable in a landscape with blue sky and clouds, especially when comparing the red and blue channel versions.

Sometimes the simple gray scale conversion and vary simpler techniques for color to b&w conversions look just as good. Picasa's simple b&w conversions can look pretty good too. Sometimes I prefer the look of the red or green channel conversions. But working with multiple channels in layers you can fine tune tonal separation carefully.

With most panchromatic b&w films we're somewhat limited and must understand in advance how colors will be rendered in gray. Choosing the appropriate filter (usually yellow, orange, red, green) for the desired tonal separation can help. But in some cases - such as using a deep red filter with panchromatic film - we may decide later the foliage was darkened too much. At that point we're committed to the negative and it's difficult to change tonal values.

But that's the challenge to b&w film and traditional darkroom techniques. If you enjoy the process and challenge for its own sake, you figure out ways to get what you want from the medium.

"I'm quite surprised that no one seems to think that there's any decisive inherent advantage in shooting the C-41 B&W..."

I forgot to respond to that part of your original question.

I really like some of the C-41 process monochrome films I've tried. Kodak's Portra B&W was lovely stuff, especially in medium format, better than any of their other iterations of C-41 process monochrome. Naturally, being experts at losing a market and alienating customers, Kodak discontinued it.

I switched to Ilford XP-2 Super and have been very satisfied with it. Besides being useful for getting reasonably neutral monochrome prints from minilabs, it can also be enlarged conventionally in the darkroom using variable contrast paper and filters.

The characteristic John A described, which I've heard from others - "I found it to be too flat and muddy for my tastes" - is what makes C-41 monochrome films very useful for high contrast lighting. It's excellent for landscapes and scenics under bright sunlight, when most finicky photographers would prefer to wait for better light to suit their preferred films. And it's excellent for flash photography, including direct flash when bounce flash isn't possible and diffusers would lose too much light. I've used it several times to photography weddings and other events when people wanted b&w photos. Everyone was satisfied with the results - including me.

It's not difficult to get the desired contrast from prints using C-41 monochrome films. Use the same familiar contrast/tone adjustment filters you'd use with any b&w film - yellow, orange, red, green. Or, if you use the hybrid workflow, scan and tweak the scans in any photo editor. Even Picasa is good enough for that. If you prefer the traditional darkroom, use XP-2 Super and use the same graded papers or variable contrast papers you'd use with any b&w negatives. C-41 monochrome films don't lock you into a single "look" any more than other films do. It's the same challenge as using Delta 3200 as an all purpose film - it tends to be a low contrast film but can be adjusted with filters, developing times, variable contrast papers/filters, or post processing after scanning.