A Mobelwagon would be about as bad as the Wirbelwind from my perspective, given the current situation. I usually don't engage in air-to-ground work, yet I have been killed many times by AA vehicles that inserted themselves into my air-to-air dogfight. In that circumstance the durability of the AA vehicle matters not a whit.
GVers complained vociferously, and still do, about aircraft interfering with GV fights, but they object to any suggestion on ways to reduce the interference of AA vehicles in air-to-air fights. I am pretty fed up with them and seriously considering active anti-tank operations using aircraft. The only thing that stops me is knowing most of the actual GV players are not the guys posting and it wouldn't be fair to condemn them for statements they may not support.