We were there a couple of weeks ago on a weekday. Yes, there were snowmobiles.
We parked in the middle of the park at a plowed lot off Deerfield Rd. Check summer map on the web, NOT the lot near the gatehouse.
We took the Bear Brook Trail. No snowmobiles. Very easy, very scenic. We kind of dead ended at the stream crossing, but we were running short of time anyway. We back tracked the way we came. All in all, we were out maybe an hour and a half.
Not sure if there is snow left after the rains. Would be nice to have a winter map!