I only let Astarion ascend one time
I was promised a Magnificent Bastard, not someone so unlikable that he makes Femto look almost compassionate in comparison
I immediately killed him and revived him, thinking that he might not be so holier than thou if he knew he wasn't untouchable
I killed him again and kept reviving him until I was out of scrolls and spell slots for sheer catharsis, and then reloaded an old save and talked him out of it
Yeah, I'm thinking of just not recruiting him at all next playthrough. This whole experience has kind of ruined him for me