So I actually dropped by Best Buy this afternoon to see if they had it. They didn't have the Warrior, but they did have the Ideazon Fang on sale for more than half off the typical eTailer price. So at that price, I just had to bite

.
(Before you all get on me for doing that

-- I didn't buy it completely on a whim. I read a fair number of reviews for it a while ago.)
So, the Fang doesn't have labeled F functions key like the Warrior, but it does have fully remap-able keys. To be honest, I mainly wanted the F keys for the F5 and F9 Quicksave/Quickload feature in games like Morrowind/Oblivion/Ghost Recon. And as it turns out, the Fang has two buttons explicitly labeled "Q Save" and "Q Load" that can be mapped to those functions.
The box included a CD with the configurator software, but the version on there doesn't support Vista, so I downloaded the Vista x64 software off the Ideazon website instead. It's pretty decent -- comes preloaded with presets for most of the newer FPS games and some MMOs. I think I saw BioShock on there, so it looks like they're pretty good about updating the preset library.
The game I decided to test it out on first (Freelancer) didn't have an included preset because it's a space sim, so I made one myself. Freelancer uses F1-F4 for actual in-game functions, not just auxiliary save/load functions, so I ended up mapping those to the top row of number keys (7-10), which I don't normally use in this game. I think that method would work fine for many FPS games too, especially the ones that use weapon groupings to map multiple weapons to one number. With UT, you still need all the number keys set to default, but I don't recall F keys being used much in those games.
The one little nitpick I have so far is the space key when I was playing Oblivion. It's mounted on the side, so you have to sort of support the opposite side of the gamepad with your pinky slightly, to get enough leverage to hit the space key to jump.
But overall, I'm pretty satisfied with it, especially after forking over only $14 or so.
Oh and, one more note. It has media keys. Which...incidentally was the reason I picked the enormous Microsoft keyboard I've been using

. I've been thinking about using that keyboard for my office, and getting a small wireless HTPC/media center style keyboard for this system instead.