I was told to take step 2 CK and don't worry about step 1. I really think its all dependent. Not taking step 1 in my opinion is not that much of a smart idea. Yes, step 2 CK might better represent ur performances as a DO student. For most places ( and u should definitely do ur research and talk to the programs themselves, preferably the directors or someone dealing with res apps), they actually want a step 1 score. I know of classmate that had to go back and take step 1. Step 1 is considered a more important exam than step 2CK when considering an applicant for residency.
While significant amt of program will take COMLEX 1 as equivalents, it will serve u best to take the damn USMLE step 1 exam and erase any doubts or uncertainty about ur chances, espicially if u looking into univ program in a moderately-highly competitive specialty.
What i found out myself is in vast contrast to what i was adviced on as a rising 3rd yr. I am a rising 4th yr now interested in surgery. Ur experience might differ, but for the sake of all ur hard work, make sure u find out urself not just what u are told. U are the one applying for the residency!