Eep. Lots of long passionate posts.
I have no problem with Jedi and gunners cross-classing. The only problem I have is when certain power/gun combinations become virtually invincible to Jedi. Namely, jetpack + jump 3 + rockets + flame + absorb 3. The Jedi can't use lightning, push, or pull because of absorb, the gunner can always get away with either the jetpack or jump, the gunner can deal damage to the jedi with the flamethrower without any way for the jedi to defend against it except keeping his distance, and if the Jedi is at a distance, the gunner can spam him with rockets.
IMO, the biggest problem in that mix is the cheap passive immunity from all varieties of force powers with Absorb 3.