In reply to Nick Smith - UKC:
I use an Epson 7800 for printing and don't usually bother printing anything at less than A2. But then most of my stuff is landscape type stuff, and that's a bit different to climbing shots. Regularly print at 40" wide on pano shots (roll paper).
Have printed Canon DSLR 6MP (two different cameras) and Canon 17 MP DSLR. There really is no comparison at A1.
Even with 17 MP, you have to up res to get to A1.
I use QImage to do all of this up-ressing & printing and it works a treat.
Big is best !