if that were the case if it really did come with the MMM combo.....those tiny servos that lock the diffs would definitely be the first thing to go along with the locking mechanism....maybe they'll have the a-arms/drive shafts/wheels to transform the e-revo into summit specs.....
I think that at 4s or 5s the steel lockers would probably do just fine, and just like a real rig you shouldn't be slamming the lockers in at anything more than a slow crawl....