Isn't the problem of those screen shots that Residual is not interpreting the game files correctly yet? That has nothing to do with the system's OpenGL engine here as I understand it.
Anyways, about those proprietary drivers;
When I started with Linux in about 2003, getting ATI to work was a complete nightmare and made your system unstable IF it worked at all. Nvidia was better, but you needed to manually compile (and recompile after every kernel update) the driver wrapper.
Now, with Ubuntu you just get a popup dialogue saying you need proprietary drivers, you can install them though that dialogue and run them (with Nvidia, with zero problems in my experience). I haven't tried ATI drivers in a long while I admit. There are however
OSS drivers for ATI now that do OpenGL except for the latest models. How how well the proprietary R600/R700 class ATI drivers work, I do not know. Perhaps someone else here has experience with them.