I found that I did not study for 2 tests. I studied for the USMLE and tacked on a tiny dose of green book and all was well. Take the USMLE, if you're ready. You will be happy you did when the time comes to apply.
Don't talk yourself out of taking the USMLE. I know more than few folks who did and regret that choice. The game is getting more competitive. You will be competing against other D.O. students with USMLE scores.