I've never tried Heretic or Hexen on the Amiga, but I remember the port of Doom running fast on a 030.

Hope you will like Breathless. It is a graphically nice game. You can even look up and down, which was not possible in Doom at that time.

Oh, it would be great to be able to play Genetic Species on an Amiga powered by a 060. I'm sure it looks very, very nice. This game was btw developed by the former democrew Ambrosia from Denmark. They have released many good productions featuring fast 3D engines.