I never really see the CPU use heavy assult mechs, just an over abundance of tech 3 mechs and troopers. Just once I would like to see 4-6 AT-AT's coming at my base and the resulting battle that would follow... Would starting our a skirmish game on tech 4 help this a little?
No. The comp only sends out mechs, heavy, air, etc. at the Hard difficluty level and the Hardest level.
I have only betean Hard twice.