...but higher res requires engineering support, and a lot of time to render out...
Hey, Grimm... just a couple of suggestions:
1) Have EA provide you with a rendering machine or two that you can have handle rendering while you continue to work on the assets themselves.
2) That machine should have as much RAM as possible -- anyone who tells you that [X]gb of RAM is too much RAM has never rendered anything at all, or has been asleep while they rendered.
3) It should also have a high-speed quad-core processor at least. Graphics card doesn't matter at all for the actual rendering, so run it on whatever in that respect.
Of course, these things are true regardless of the render, but I am sort of curious... What are you rendering that's taking so long in the process?
I suspect that whatever it is won't have a lot of specularity (if any at all), and while I'd expect there to be decent bump or normal mapping going on, I don't suspect that to keep UO looking somewhat like UO that you'd be doing anything with photon emission and very little with object incandescence. Particle effects maybe, though it would make more sense to apply them inside the game engine itself rather than as renders so that individual graphics cards could make of them what they could rather than hope the animation looks crisp.
What target resolution are you rendering for? I could see shooting slightly higher than 1920x1080 for screen resolution since there are a small handful of us that run monitors large enough with enough pixel density combined with video cards that actually support that kind of resolution, but... even at a full-screen resolution of 1920x1080, I'd think most of what you would be rendering would be at most a quarter of that height, and most significantly less than that, because there's a need to have a lot of stuff going on in that space... though, obviously, if you zoom in, I suppose half-height wouldn't be bad. But when you're talking about a 540px height render, if it's a static (yes, I see some of what you're doing is animation, but since it's frame by frame...), then I would think probably no more than 5 minutes a render on a slow modern machine... presuming you're rendering for animations at roughly 60 frames/second, and presuming you decided to do 1:1 ratio on the animation (most don't, by the way... most do a 1:2 or 1:3 ratio of different frames per each second), you'd be looking at approximately 5 hours per animation... 2.5 at a 1:2 ratio, and about 1.6 hours at a 1:3 ratio.
Long series of questions and comments short... I guess I'm wondering why the render process would be what's impeding things. I'd think the animation and asset build on more complicated assets would be worse.