I almost guarantee that if you don't like C-E2's at 3.7v, you will hate them at 5v. I've tried a 2.5 ohm carto on 5v and it's horrific. It's good for a dry burn though. I find them pretty good at 3.3~3.7v once properly broken in. 100% PG works best IMO, or at least a PG heavy mix.