If you're talking about vacation, and not just time off, see below. ED shift work almost certainly works out to less hours on the job on average, but at the cost of more nights and weekends.
Vacation time is very job specific. Most anesthesia jobs I'm aware of are 6-12 weeks. The most I've heard of was 17, in a less desirable location. I don't know what the average number of ED vacation weeks is.
Having said that, the nature of the ED shift work would probably make it easier to find a part time job where you could work 1/2 time, take extended vacations, etc. But, again, that would be very group dependent.