W'rkncacnter
Hero
the subclass/prestige class change alone would require rewriting all the subclasses at minimum, and most likely the base classes as well. removing absolute abilities would require a similar overhaul.
One thing I would have done is somehow combined Concentration and Attunement.I'd rework how the Concentration subsystem is applied. It cut out too many buffs, when a short duration would probably be all that they need. Then how it was applied to the spells was another issue - in practice, it often end-up being an "This is an out-of-combat spell" indicator. Moreover, because of it's often short-term expectations, if you could work a duration longer than a round or two out of a concentration spell that was intended for in-combat, that spell often went from "worth-it" to pretty near "absolute best in slot". Often to the point that there was no reason to have more than one combat concentration spell in a spell level, as only the one would ever get chosen.
None of the stuff the OP mentioned is in Level Up. It does, however, fix a few of the problems found in 5e.Not that familiar with level up advanced 5E, does it do the things you are looking for OP?