In addition to some random models I've just done on impulse, I have largely completed all the L1 units (of every kind), all the factories for every type of unit, and most other structures.
Thus far, I have largely completed 62 models. Here are two which I am very satisfied with, though I may still tweak them a little. I am not posting the rest of them for a bit. Frankly I'm too lazy to take that many screenshots... and some of them are missing an arm or a leg still...
Core "Thud"

Core "Storm"

In order to make the texturing process a little easier on me, I'd like it if any volunteers for making metal textures would PM me. It'll be a while yet before I'm to the texturing stage, but I'm working on a way to make the process very quick while still maintaining quality. Also, any relevant texturing tutorials that you think would be helpful would be appreciated... I'm still very new at this texturing thing!

Because of the modular way that AA is set up, these will not be a forced download. You can still use the low-detail models if you choose, by just not downloading the "High Definition Pack". These will be a part of RealOTA eventually, as well. Filesize is not going to be a consideration. I'm expecting the main content file to be at least 80 MB, with patches and unit descriptors, etc, etc, being much smaller... 1MB or so at most.
Now, onto the question everyone's going epileptic over: Will my computer be able to run it? There's a complicated answer, but the simple on is, probably. In my experience, what kills performance is NOT polygon count (model detail), but the other functions of the spring engine, such as LoS calculations and pathfinding. There is an effective limit of about 500 mobile units for the average computer, since beyond that, your CPU just won't be able to handle all these calculations and will degrade gameplay severely.
So: if you can run Spring now, you can most probably run Spring HD with no noticable decrease in performance unless shadows and reflectivity are turned on. Reflectivity won't be too bad, maybe causing a 25-40% drop in performance compared to what you're used to. Shadows will probably cause an additional 25-40% drop.