I've recently switched my commute route to incorporate the Elyria to Oberlin portion of a rails-to-trails MUP. Doing so allows me to avoid some narrow roads with high speed vehicular traffic (and a lot of crazies). I have had no problems on the path, in fact I would say it is pleasant. I usually see 15-20 cyclists, 3 or 4 roller bladers, and a few joggers. In fact, on my commute last night the best parts were exchanging pleasantries with the roller bladers and joggers.
All of the MUP intersections with streets and roads are clearly marked and controlled by stop signs. The path does go "cross country" and does not parallel any roads making the crossings not near any road intersections. I do have to ride a couple of busy streets to access the path but for the most part I can move suffiently with the traffic to avoid having any issues. I guess it all comes down to how well the path is planned and how well it is controlled. And how well the users of the path "follow da rules".
'bent Brian