yes, worth the exploration (although I'm not aware of the trail condition or rideability at this time as I haven't been out there in a long time...)
but, just to find the areas mention, go to just about any Mi DNR operated/state owned facility, and get their land and rec. area guide for free. It might have a map showing at least the areas controlled and governed by Ortonville/Metamora State Recreation Area, that way you can see which roads to take, or surround the areas, but I'm positive the trail maps they have of these areas are super limited...
jbodyaudio - most of the other areas are just north up Hadley road which you pass on Oakwood by a greenhouse garden center, then you go for a ways, around quite a few curves, past Big Fish Lake access, then you get to the top of a big hill on the road, and there is Fox Lake Road crossing, and you can go either way on that road and find several trails and orv areas, but the most (Hadley Hills/Pinnacle Point) will be to your left (west). Go down Fox Lake rd for a ways, then you will pass a very large (looks like a picnic area) horse mounting/loading area on your right, you can pick up to most of the trails from there, or keep going down the road until you get to a 90deg corner, and keep going straight on a skinnier, small 2-track, and just park and go from there. Awesome area, check it out.
I likey da' bikey.