dseelig - if you're referring to the desktop Canon's, than they use about the same amount of ink as the Epson P800, but the Canon's agitation process can use a bit more unfortunately. Just curious; how do you get that Epson doesn't use as much ink as Canon? It's actually the opposite from our experience and from many of our customers experience. Canon uses less ink (especially on larger models) than Epson.
The quality difference between the P800 and Pro-1000 can be slightly different if you have a keen to color detail vs what the screen shows (properly calibrated). Otherwise, having them separate with all the proper settings and profile will almost be hard to tell apart. Since we also create custom profiles, we tested between both models with a few papers and it was a bit hard to see the differences (not that there wasn't any). So, as others state, a manufacturer/custom profile with best setting "should" provide the closest look of what the screen shows; and that's for either model.