Regarding "permanent" that I've emphasized above...
This may just be a gaming group thing, but if a player in our group makes a choice when creating/leveling their character and a couple of levels later it's not working out (e.g. "Dang, feat ABC I picked a couple of levels ago doesn't work at all like I thought it did and it's messing things up."), we usually just let them retcon their choice. For us, it's fairly easy to work this into the roleplaying via a retraining sub-storyline.