I have done IME's in the past and have found them to be fairly easy. They are pretty much the same as a very detailed history and physical. Some include tables and graphs, but that would depend on the account. I would do it if you have low work on your other account. The reports tend to be very long, so pretty good for a line count.
As far as compensation, I wouldn't expect it to be higher than Acute Care or Surgery. I don't know what your other account is, so nothing to compare it to.