First of all, COMLEX and USMLE scores won't start coming out till next month. And you can expect a few months after that before schools start releasing their reports.
Yes, ARCOM has definitely accepted sub-500 MCAT students, but I can also tell you I haven't met a lot of people with less than 498 get in either. I think the average for my class was 501, and I've also heard the average has risen a little bit this year as well (probably 502 or 503). Just FYI this is the norm for DO schools all over the country. That's why they always say DO schools are more forgiving, and are willing to accept students with low GPA but great MCAT, or low MCAT high GPA. ARCOM average GPA is 3.54.
For the statistics, I think from recent studies they determined that MCAT was a fair predictor of Step 1 scores, but the greatest predictor of Step 1 was performance/grades on pre-clinicals. Also from a study done by AAMC with a score of 498 or higher, there's no significant difference in performance at least for year 1 (page 19).