Could work, do consider the fact it takes a bit of time to get level 3s up if infantry do it themselves, also potentially precious time if commander researches them. Turrets also don't do a whole lot endgame, so you have to ask if having to research turrets is worth an early game advantage. I am just saying that because while lvl3s are kinda annoying, the effort it takes to get them feels like a fair tradeoff.
lvl3s are actually really lame endgame, as anyone attempting to ninja in any way is about to have a bad time.
I don't see the problem with that, the commander took the time to research and build those turrets. Ninjaing should be a very risky endeavor, because it relies so much on just a few people it makes sense that it can be stopped when the commander spends more of his time on that defense. Turrets are kinda useless I feel when heavy tanks start rolling. Although now that I kinda think about it mgs tend to stay alive for longer just because they don't shoot tanks, warning them that there is a turret.
lv3 mls are a joke to heavies unless you can get a large mass of them. IF you do... you just gave that heavy driver a ton of points to pick up. They should launch 2 mls at a time instead of one thus doubling the firepower. They should also no longer target buildings. <dun, dun, DUN!>
Added. It's the same key as whatever you have +emp_comm_mselect to, which I picked because it's shift by default.