I think the fact that the lightning whip one-shots every non-grid objective is what heavily hampers them from being one of the strongest squads in the game. With that penalty, they are middling compared to other squads, because it makes getting bonus objectives, or generally handling cluster situations that involve those non-grid constructs or the other mechs (if, say, they are webbed and cannot move away), extremely frustrating to deal with. Especially the train missions turn into an absolute pain, as oftentimes, Vek surround it. As if defending the train missions weren't already difficult enough.
It's especially bad once you get to the third or fourth island, where it's very easy to get overwhelmed by Alphas and lose bonus objectives with them.
Edit: Also, I've been thinking about writing up the merits and flaws of each of the regular squads, maybe even all of the mechs, not sure it'd be worth bothering with though.