I have an FJ-50 and I converted it to use mild solvent inks.
I had an encad before this (waterbased pigment) and I can tell you that as a signmaker, you'll definately be better off with a solvent ink system.
The conversion is fairly simple. You don't need to change printheads or dampers or internal tubes or capping station.
You just need a long life pump and change some tubing.
There's a lot of other thing to know too though!
If you decide to go this way, I'd be happy to assist.
As far as I know, there's not many other users out there running mild solvent hexachrome inks! But I am really happy with the results I'm getting.
I can print photo's straight to gloss vinyl that look just like an enlargement.
The printer will handle full 1370mm width banner stock.
I can print bumper stickers, fridge magnets, full color banners on uncoated material, vehicle wraps - anything that the Mimaki can, albeit slower.
So overall they're a good printer, but much more useful with mild solvent inks.