Well since I already knew this was coming I guess I'll say it again: this is a fucking great idea (if you'll pardon my French).
Stats like flat & % attributes, resists and + skills are the biggest offenders on the charms in my opinion. Since you already covered these in your example my only hope is that the gap in the "All skills" rewards and the "All skills + class skills" levels will be lowered significantly. I think oskills are a great feature of the game and having them being at least 8 levels lower by default (13 if paladin) is a pity. For example the sorceress has great tools on her tree to support oskill builds, but none are popular right now for that reason (among others).
I hope that after all is said and done with the patch, the overall game difficulty will still be high. That is one of the main attractions of median - challenge is fun. The best approach to take, in my opinion, would be to actually "undernerf" the monsters on release. So releasing the game with slightly stronger monsters overall than originally planned. This is because of the whole "negative bias" aspect. If it turns out that this is a good balance level - great. If, on the other hand, you have to adjust monsters to be slightly easier a few months after release it won't cause any community drama as buffing the players is seen as a positive outcome. Alternatively if the patch is released "overnerfed" and monsters have to be toughened in a few months to prevent facerolling there will be unnecessary drama in the community as it makes players weaker because you, in a way, reset their achievement capabilities and it is a negative effect.
That being said Marco wouldn't have come up with such great balance changes/paradigm shifts if he didn't already realise how to execute them properly, so I believe he will make mxl2016 really something special.
PS. the "high numbers" paragraph does not read correctly. You make it sound as if high damage numbers cause sprite limits/disconnects when those are only a function of skill mechanics, creature density on screen and procs.