Nice tactics mate, but you forgot two basic things:
First, the excact mod is very "friendly" with the natives, since the Zaarin is taken as friend both by locals and by rebs. In other words, in the final game, if you still can raid planets with imp heroes (didn't know this, good find indeed - i use a lot rebel raid fleets when cant take out the space battle), the locals won't be your "loyal" mates that will go right in the heat of battle just to capture those building pads. Also, the AI will attack their spawn houses (it does this when it's in the attacker role) so, you're left with 2 heroes on a planet where everyone wants you dead.................i don't know if retreating is available, since you'll normally fall on the enemy fleets on orbit (i tried this once, while evacuating a planet...).
Secondly, personally i don't like these battles where my main units are the natives. In the mod, if you don't pay much attention, you end up controlling natives, which turns to be boring.......i like to fight with pure reb/imp forces, and to use those natives just to take out a patrol.
Non the less, i really like that imps have such "raid" ability