Im partial a little since my Backstabber took out Han, but I see what you are saying. Plus I think Backstabber is better than MM.
I agree, Mauler's reckless obsession to get within range 1 usually leads to an early death for me. Now the large ships having more firing arcs (YT going 360 even), it's harder for him to get in range 1 and not take a range 1 attack back. Backstabber can at least kite the big ship at a distance and hopefully survive a little longer. Also Backstabber seems to solo better.
Regarding Alpha vs Mauler, I think I'll take an Alpha every time (I've had terrible luck with MM and need to switch to something else). I don't see the high pilot skill being enough of an advantage since it can be mitigated with swarm tactics or squad leader from a high PS wingman. I could see an argument made regarding taking Mauler + PTL over an Avenger Squadron pilot because the double action can give Mauler a bit more flexibity over the standard interceptor.
Something else that just came to mind- so far we've been basing this discussion on what would you take when building your squad. I think the results would take a different turn if we looked at it during an actual game and said what ship would you rather have as you last surviving ship: MM or Alpha. I think Mauler might get more votes if he was your last chance to win the game.
Another Hypothetical: two players are down to their last ship each, one has Mauler + veteran instincts, the other has an Alpha (both undamaged). Who wins the match? I think most can agree that Mauler has a higher chance of winning this set up given equally skilled opponents.