Random neonstorm:
1) Nerf resurrect so it has minimal discount. You pay the remaining metal and energy to convert the wreck back into a unit, so there is no net metal discount (lots of BP discount though since you don't have to reclaim the wreck and it's already effectively 2/3 done).
2) Let caretakers resurrect.
Then caretakers are your fast-comeback-mechanic. Energy and BP are in resources in shortest supply after a near-wipe, so that's what rez needs to conserve. Metal, on the other hand, is plentiful in the form of wrecks, so that's what resurrect would be least-efficient with.
Resurrect avoids the nanospoofing problem since wrecks don't have nanoframes. Of course, the obvious downside is those nasty caretaker-farms around heavy porc putting the porc back up as fast as you can destroy it. That is exacerbated by the fact that wrecks go straight from untargetable to fully-active, so it might be necessary to hack in a starting stun or something, so that resurrected units are still vulnerable/useless for a bit after being rez'd.