I think a lot of this will fall to the wayside, as more and more use Lightroom to do the conversions, using the new B&W controls in raw conversion, and the advanced B&W dialog in CS3. Personally, nothing beats getting a good exposure to build a good digital B&W image from. Also, the conversion method seems to be the least important of all the steps in making an effective digital B&W. Personally, the channel mixer and the LxL method Rense describes works for pretty much any well exposed image. A few things to remember about CM conversions: green channel is great for skin tones, red for rocky landscapes, and blue can be quite dramatic in scenics with people. Really, it isn't so much about what method is better, as you say, but what's easiest and allows the most tuning. Speaking of tuning, The big difference in an digital B&W that makes or breaks is is in the finishing touches: localized contrast, burn and dodge with an overlay, using all the 256 tones, where the predominant tones lie, sharpening, blurring etc. martin Henson has a pile of good information that shares a few of his and others' secrets:
digital-monochrome fine art black and white landscape print galleries.
There is a cool graphic here that aligns the CM with the results to show how the final product can be tuned:
Digital Black and White in Photoshop - Photo Tips @ Earthbound Light
Finally, one of my favorite resources, TLR. There is a ton of good info here, including fine art B&W, toning, sharpening, didge and burn, etc.:
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