My skill never exceeded 30. Honestly put, the late game of MM6 and MM7 alike is not that fantastic from my viewpoint — it's mostly lots and lots of combat, which is quite mindless in MM's. Hence, most of the late game reduces to a "brick on 'A'", and by the time I blow up the Hive, I'm glad it's over. So I'm definitely not the one who would extend the game too much behind its "natural" length.
And at level 30, it just isn't worth it. To bring down one gold dragon, you need 3 "perfect" (with all 7 missiles) hits on average, and that needs 150, but more likely 200 mana. It's nice that my characters have 1000 mana each, but even that won't last for long (if we add all the buffs, healing, flying etc.) I like more sustainable solutions.
With all of that melee, I could swarm the dragon with so many attacks that he wouldn't be able to respond more than 2-3 times. I can deal with him face-to-face in turn-based mode, just take those attacks, and spend 30 mana for a Power Cure occasionally.
(By the way, I have the same problem with Peter's method of clearing Darkmoor. Dragon Breath is awesome, but all of my characters' mana is sufficient maybe for a single hall of eyes.)