I actually used Mas and 2 ugs. And I went 3-1 not 4-0. I lost to Eric's General Skywalker and Yoda on Kybuck, but not for lack of squad strength. I was like 0-6/7 on block and deflect saves, and Yoda ended the game at 10hps. Actually, he was at 10hps from about mid game on I think. Rolls just didn't go well, but it's a solid squad regardless. Hard to top that much beef in 150pts.
Also, Mas used cunning momentums in the late game in virtually every round and they were absolutely key in at least 2 games. In this, Mas isn't particularly needed after the mid game for booming voice, but is incredible helpful if you have to chase down a shooter running away from you early on. Once you've engaged, Mas can move up and fight with the rest of them. I usually held Mas for one round, then charged behind everyone else