I've just had an R2000 printer on loan from Epson UK and have just written up some notes and comments if anyone is interestedhttp://www.northlight-images.co.uk/reviews/printer/epson_r2000.html
For a printer that I'd expected to put into the 'nice colour pics' category, I was genuinely surprised at the quality of B&W output, given the CMYKRedOrangeGLOP ink set (pk and mk). The B&W print mode (not ABW) was so-so, but with a custom (colour) icc profile (~3k patches i1 profiler) it looked very presentable.
A direct comparison print made with a multiple black solution (Canon PRO-1) needed to be viewed under very good lighting and close up to easily see differences.
I do occasional talks for local camera clubs, and took both prints (A3+) with me (unlabelled) to a recent talk (about digital B&W) and asked people to tell me what differences they could see - if any. In normal room lighting (very mixed), the results were not what I'd have expected before testing the printer, and to be honest it took some care to tell which was which myself from a reasonable viewing distance.
I'd not for a moment suggest this route for people wanting good B&W prints, but it does show just how good current printers are getting, and makes it harder for me to find meaningful
differences and improvements when looking at them.
Anyway, Canon tell me that an iPF6450 is going to turn up at lunchtime, so it looks as if more testing is required :-)