I just thought I'd share my Epson 3800 experience after 2 months, these types of posts were very helpful to me in my research.
I can't add anything to what has been said about print quality, of course it is outstanding. But I jumped up from an older Canon dye based printer so there probably wasn't any possibility except to be impressed.
For the first month I turned it off when not in use. I made probably 40 prints sporadically between 5x7 and 17x25 in size. I live in Austin, it has been very humid this summer due to the excessive rain. I did not experience any clogs. I run a nozzle check on plain paper from the printers control panel every time I power it up to use it.
Then I went on vacation for three weeks, I set my thermostat on 85 to save some money. I covered the printer with a blanket and unplugged it. When we got back it was ridiculously humid in the house because the a/c didn't run much when we were gone.
I ran a nozzle check and had 4 clogs. Three head cleanings later everything was cleared out, no power clean was necessary.
The Advanced B&W mode is really nice, I highly suggest trying it out.
I highly recommend this printer if you are considering it...