Watched a few streams. Perhaps it would be better to keep the rule prohibiting the use of the "Enhance" spell and Grand Vampires in SoD. If one player gets a Necropolis and the other doesn't, it's game over. And if the Necromancer is weak (like Nimbus), it's not necessary to make him the main hero; you can give him the Grand Vampires so he can collect skeletons, and the effect will still be very strong.

Added after 2 hours and 23 minutes
And regarding the HotA mirror matches, wouldn't it be better to play them on faster maps? Especially h3dm1, where the distance to the opponent is slightly greater than on the Diamond map, and contact occurs later.

If anyone is willing, please play some matches on fast maps and some on medium maps, and then compare your impressions.