just my thought...
if you would like to do any sort of competitive residency i'd suggest taking both USMLE and COMLEX.
true, if you only want the option of DO programs than COMLEX alone is fine
but why not take both exams and open up more doors for you.
with that said, taking both tests is a double edged sword. if you do well on COMLEX and do worse on USMLE, then people will just validate that DO students do worse on USMLE than MD students (granted that we are taught for COMLEX style questions). so if you decide to take both, you need to do well on both.
as for the two tests, i thought COMLEX was easier than USMLE (mainly because USMLE had better questions). it's true that our DO training gears us towards COMLEX but it also prepares you for USMLE very well. i just studied the same for both (FA and USMLE Qbank) and spent an extra day of reviewing biochem and molecular genetics for USMLE.
i know it's a drag taking both exams, but you'll be very glad you did when it's time to look at programs and you hav double the options with your USMLE scores.
on the flip side, i know of a anesthesia resident at a very prestigious anesthesia program who didn't take USMLE (but aced COMLEX)
oh, and it would help to contact the programs you're interested in now and ask if they take COMLEX or require USMLE (some will even tell you that they take COMLEX, but that you should take USMLE to be competitive). also keep in mind that you might be set on anesthesia now...but who knows what will happen and you might change your mind and will kick yourself for not taking USMLE then (happened to me, very glad i did both).
pm me if you have any questions about either exam.