You guys are doing a great job, trying to remove the element of randomness, etc., and delving into complex aspects, but what about removing the simplest imbalance... for example, limiting the bonus from a hero's specialization to a maximum of 100% (level 20), and there won't be any Thorgimms with 100% spell reduction or Devilish Logisticians with 5k+ movement points, impenetrable Tazar units, or scouts from the Dungeon faction at level 30 who can see the entire map.
The problem with hero specializations in a team was briefly mentioned (and not only in relation to the Dungeon faction), but this specific solution wasn't considered. The idea is interesting, although there are still some questions about it in this form (if you're interested, I'll elaborate later), but overall, your post raises the probability that the problem won't be completely ignored.