I've worked both. Pre-op compares nothing to the ER. Pre-op starts busy from about 5am-8am, then nothing. but it's a nice change of pace. You get to take a lunch break, and I didn't have to work any holidays. I'd say if you're getting burnt out in the ER, try pre-op. Now I work in PACU and I really enjoy it. I still do some critical care, but the pace is much nicer