I found this to be the only way to run in D3D.Ren mode without the FPS drop or system crashes/freezes. Had to copy the DLL files directly to the game folder, though. Might be a useful tip for those wondering what to do with them.

Did it make Blood 2 actually playable?

If you're asking about dgVoodoo, then yeah, it runs (for me anyway) with settings set to high. I don't have it running at full resolution because I don't trust Lithtech 1.0's stability with my current monitor's natural resolution. FPS is fine, but the game is still pretty damn buggy, and will crash at random, especially when I close the game itself (funny enough).

There's no harm in trying this, or the other methods listed above. I didn't mess with the Configuration tool that comes with the DLL files, so if there's anything inside there that makes things work better, might not be a bad idea to throw your dgVoodoo settings up in a reply in here.