I think that the turbo patch doesn't work with the RTG version of the game.
In terms of playability i find the first AB3D superior. The main advantage of AB3D 2 was the improved graphics.
The most technically advanced Amiga FPS games (excluding ports like Quake) are, imho, the genetic species and perhaps Trapped 2.
Edit: I can't find xenium core on Aminet.
