Mana gem and surge should allow you to pump without ever having mana issues. The only positive I can see with evocate is you get full mana surges off, I’d be hardpressed to find a time when you dump your mana fully with how frequent clearcasting procs are.
If you push for charged orb and then go down 1 tier beyond enlightened. Then mana gem you’ll be set for leveling. Up til 70 maybe grabbing evocate works, but I’d judge how often moments come up where you wish you had it.
At 70 I wonder if running tempo (haste on charge spend) and arcane harmony and orb barrage capstones will be viable for group content. Until mastery levels get higher and you can load more damage into kyrian & magi.