My 2 cents:
1) The XP loss is too severe. It isn’t fair or balanced to lose 25% XP just because a mob turns at a split second and everyone has run off to an NM. 10% loss would be an improvement, but I think most people would like to see it gone altogether. It does nothing but reward griefing. Put on a weakness timer or something....
2) I actually don’t mind the grinding, but it may help to add level sync, so it’s not too punishing for groups to be more than 2 levels apart. I already feel like I’m falling behind to much to get in a group, and I’m 25.
3) The XP required to level is really steep. I kind of just want to see the story and the NM fights; I’m not too hung ho about the relic. Maybe make it a little easier to level and a little tougher to get the relic?