After much to-and-froing, my own Canon/Epson/HP decision finally got resolved in favour of HP. It's only six-colour (not their latest eight-ink unit), but the biggest difference there would be if I did a lot of black-and-white printing.
The single biggest factor was my fear of printheads clogging if the unit sits unused for a month. At least on the HP all I need to do is replace the ink cartridge (and if I know that the printer isn't going to be used for a while I can take the cartridges out and store them in a ziploc bag). I also like the fact that HP seem to have standardized on one regular set of print cartridges for all their various models, so if I get a smaller printer as well as the wide-format I would only have to have one set of ink cartridges in use at any time. The Epson would be my primary choice for print lifetime, but it's twice the cost of the HP ($799 instead of $399). That difference buys me quite a few reprints.
