canon color imagerunner IRC5180 vs. IRC3320

Which is a better printer, the IR C5180 or the IR C3220 that came before it?

The IRC5180 specs say it is faster, 1200 dpi vs. 600 dpi (though copy is still listed as 600 dpi, engine resolution is 1200 dpi which I don't get), and is supposed to have better density.

But it seems there are a lot more 3220s installed.

I'm wondering how technology such as the belt fuser vs. roller fuser, etc. affects print quality?

Is there anything better about the older-design IRC 3220 or is the 5180 better in all regards?

Which is cheaper to operate?