Fred:
I'm not speaking from 1st hand having been there in the last day or two (I WAS there a week ago, but this is Michigan and 1 week can certainly change things) but there was still too much snow (then) to ride single track - even with the warm days so I'm going to guess that there STILL is too much.
However, further south/west - Horseshoe, Holton, and Cedar Creek were 99% dirt this past weekend and a great ride without studs. It'd be a better bet in my opinion to try one of these.