I also do not recommend generic or refill inks for printers, as I had an HP printer ruined by them. I prefer the separate tanks for each color as well, for the simple fact that they don't make you waste ink. I have gotten over 40 8x10s out of one set of ink tanks, but it varies widely with color saturation and picture content, so I don't think it is possible to give any accurate figures for usage. Another plus for Canon is that the print head is not a part of the ink cartridge, so you don't have to pay to replace that every time you replace ink tanks, unlike some other brands of printers. While there may be some value to that kind of system, Canon's system is less expensive to the user.
The ink doesn't seem to dry out very fast with long periods of inactivity, although it is better for the printer to use it regularly. I also like the fact that the low ink warnings give enough time so that one can plan one's usage carefully to maximize what you have left and not run out of a color in the middle of a critical print.
The great thing about buying all three cartidges at once is that you have a supply of refills waiting. The drawback, though, is that if you use one color much more than the others, you are better off buying that cartidge seperately versus buying all three in one group.
