If the Mangler Cannon's crit effect were worthwhile on its own, we'd see Winged Gundark used much more often, and we'd see Marksmanship popping up everywhere. But we don't see that, and in fact we have years of evidence at this point suggesting that crit-fishing is not a strategy that's well compensated in X-wing.
So here's the list of ships that benefit substantially from equipping a Mangler Cannon. I'll update it if someone comes up with an important addition:
- Heavy Scyk Interceptors (it's better than their native 2 Attack)
- YT-2400, with or without the Outrider title (it's better than their native 2 Attack)
- Ten Numb (who can use it to create action-independent unblockable damage without filling the EPT slot)
- Imperial Kath (who can use it to force a choice between taking stress and taking critical damage)
- IG-88B (who can use it as a pseudo-Gunner)
- Krassis Trelix (who can use it as a pseudo-Predator)
Before... yes. Now small two ship builds are becoming the norm. Crits can wreck a Decimator's day QUICKLY! With 8 hull points, Han isn't going to like all those crits either. Not to mention how it can help finish off a badly wounded ship. Bombers loose abilities and ordinance. HWKs loose abilities and their turrets. Direct hits finish of Ties.
Welcome to the new meta. Crits and stress are a thing now...