One more thing about high level magic.
Fireball deals up to 10d6 damage(cl = 10 - tier 3). Cone of cold, deals 15d6(cl = 15, tier 5) and Meteor Swarm deals 20d6 damage and is a 9th tier spell. Going from tier 3 to 5 gives +5d6 damage. From 5 to 9, +5d6 damage. Is a huge bonus but is not game breaking like some people portrait.
And on 5e, they reduced the difference between high tier and mid tier spells by far Cone of cold deals 8d8 damage and fireball, 8d6. Also limited the usage of high tier magic, so a lv 20 sorcerer can no longer cast 6 reality shaping wishes in a row. Increasing the lv cap to 11/12 will not going to be a problem.
There is no spell scalling also. Low level spells lose their usefullness unless you cast them using higher spell slots, which creates a tradeoff since doing that you can't cast more high level spells.
