I'm using a 4000 that has sat for the last two plus months and after a few cleaning cycles, it's printing like a champ. My 9800 sat a bit less and it's also fine. I haven't tried the 7600 in a few months but I'll bet after a few cleaning cycles, it will, too.
I'm in California and where there is low humidity and haven't had a major issue with clogging. Same for the old 2200 (maybe 10 years old) that sits down the counter and still produces lots of smaller prints.
Though some have had problems with clogging, not so with me!
Of the four Epson printer I have (only the 2200 and the 4000 were new), clogging and most other issues have been minor. The 2200 was rebuilt a few years ago when the chip hit 6000 prints and became a brick. It needed new waste pads and a chip reset. This year it needed the rollers worked on and cleaned and it's ready for a few more years.
My 7600 was second hand and the carts interchange with the 4000. I bought it to do larger prints and as a bonus, the ink carts interchange. My 9800 was used commercially before I bought it and was serviced by Epson before I picked it up. It has worked flawlessly in the two years I've had it.
Of the four printers, the best and richest prints, including b&w, come from the 9800. I use the Bill Atkinson profiles and the prints nearly match my monitor. I seldom have to reprint because of monitor-printer differences.
Once your matt and frame the prints, you'll see very little difference between the output of most printers, though with the new inks and winder gamuts, you'd probably see some differences between them if you put them all up side-by-side. Each printer/ink/paper renders slightly different.
With most of the pro printers of the past few years, the quality is simply stunning, IMO.
Between my 7600 (9600) and the 9800, though, the prints are much richer and the b&w better with the 9800. Even at under $1000 for a used 9600, I would probably track down the 9800 (or even a 9880 with Vivid Magenta) and pay a bit more for newer technology and the K3 inks. Parts and inks are going to be around longer for the x800 and x8800 printers than for the 4000/7600/9600 printers, though I know a few photographers still using the now ancient 7000/9000 series printers and print nice work.
If you are going to spring for an Epson, look for a 9800 or newer. Less chance for clogged nozzles and better, denser inks thus richer prints. Though the x600 produces very nice prints, you will be happier with the print quality of the x800 series since it is nearer that of the HP 3100 series as far as gamut and d-max.
