I already said I DON'T use Attack Pattern Beta, and I still out-DPS everyone else I come across.
I still get high-critical hits with my Torpedos with my Engineers and Science officers. I still see hits of 15-20k with them.
Energy weapon damage is significantly lower, but putting an Engineer in an Escort gives you ways of increasing your power levels plus that extra shield heal for survivability. Makes for a pretty good PVE setup actually, I love using my Klingon Engineer in a Siege Destroyer!
Firstly I didn't mention Attack Pattern: Beta.
Secondly as your power level doesn't effect torpedo damage I fail to see how being an Engineer would allow you crits similar to your Tactical captain.