Happy R1800 user exploring larger formats

[Terry Cooney]

I've been reading through the numerous posts conatined herein regarding the Epson 3800 and the Canon IPF5000. I presently own the R1800 and am very happy with it, but I was exploring the possibility of a large format printer.
Here's what I do:

99% color glossy, usually the maximum paper size, roll adapter not needed
Average of about 3-4 full size prints per month

1) Ideally, I'd like a 17" R1800, but barring that, would I be able to produce the same quality of prints using either the 3800 or the 5000?

2) What's the generalized installed ink cartridge longevity for each?

I'm thinking that either of these might be 'too pro' for what I do, but I love the control over the process, and I'd really like to produce a good looking 17" print.

Thanks!