Here are my thoughts for the new combat system as someone with all achievements.
New Game+: Very easy. An even easier late game with how sigils and buffs stack with the new combat system. Any builds work at this point.
New Account:
1. PURE:
Painfully difficult to start. The only enemy you can beat, as pure, is the slime and that's if you don't change the size of the slime. You're forced to add points into Prowess until level 5 before tackling Torgar and The Bind, eventually to level 15 with hyper endowed and tank (or berserking). You'll also want the level 10 cock ring buff or spam the Sigil of Growth infinite stack exploit thanks to the new timeline combat system. For limit breaks, you respectively get 7 cock size, 6 ball size or 5 muscles, and 6~7 height for last.
2. CORRUPT
As corrupt, most things don't matter. You still need Prowess, but you eventually get OP corruption skills for damage. Combined with Sigil of Growth, you get all the size and stat growth you need. Echo is optional and muddles your skill list, to be honest.