I did get a proof and the black and white photos came out beautifully. But they weren't greyscale images; they were RGB files converted in CS2 to B&W, so I can't really answer your question accurately. Noah Grey's book "California" is mostly B&W and looks fine, too. But I doubt he was using greyscale, either.
I've found using greyscale instead of converting to B&W via channels or filters to be very poor quality by comparison. Not with Lulu, just with digital B&W images in general.
Sorry I can't answer more thoroughly!