Those single maulers have me intrigued... do you think the mauler works for actually punishing lowered shields, or making the AI do what you want it to?
Oh sorry never responded to this. In sim, yes the Heavy Mauler does seem to prevent the enemy AI from venting (without it, the enemy AI just disrespectfully vents in my face, since I wouldn't have any anti-armor). I'm not sure if it really affects it that much in fleet combat though.
Rather, it's so that my ship has at least one weapon for anti-armor. Anti-armor is different than anti-shield or anti-hull. In the other cases, you can pretty much just sum up the damage from each weapon. But for anti-armor, what's most important is whichever is the strongest. So the single Heavy Mauler provides the anti-armor role. The HVD will provide nearly as much anti-hull as the Heavy Mauler, but far more anti-shield damage, so it's more useful to stack HVD's.
In this case, in theory my Cobras provides anti-armor (and anti-hull...and anti-shield), but I was never good at timing fighter strikes. So the Heavy Mauler provides some backup anti-armor capability in between Cobra strikes.
And yes, I'm looking forward to Legion with Sarissa as well, along with Prox spam. Although in the end, I ended up piloting Onslaught XIV so that I wouldn't have to worry about timing my fighters; but Legion with Sarissa might work well too.