this sounds fantastic! ive always felt that there is a sudden change in difficulty and xp and this will (hopefully) make progression much smoother and more enjoyable.
my only worry is that lvl requirements might make it annoying to lvl for access to ubers, but knowing you a bit, im quite sure that it wont be a problem
hopefully some similar changes will happen in terms of early game gear acquisition so that it will be more fun to start new characters and rush it p1. ive always enjoyed starting from scratch, but some chars are just much better than others to blaze through the early game; eg bowzon got a ranged attack and a good bow will carry her quite far while she can more or less ignore most other equip slots. by comparison a close combat char has it much harder to get "equip material" for because you need to worry about both good weapon and defense so usually it requires more early game farming which makes it uninteresting to use them in an untwinked speedrun for fun.
im also looking forward to see how uber lvling in lategame will turn out, it sounds like a cool concept
thx for the update, was a good read