There's one that I use for a couple of miles that sounds very similar, with one BIG qualification: there are only a couple of cross streets in the 2 miles of the path. Most of what's on the other side of it is park or undeveloped land.
The parallel road is narrow and busy. I don't have a problem slowing to <10 mph to use the MUP (which you pretty much have to do to be safe) for the mile and a half between my house and the main road. It's plenty wide for two-way traffic, and intended for that even though it doesn't have a center line.
The parallel road is narrow, shoulderless and busy; the limit is 35, but because of the absence of cross streets on one side, most people do 45-50.
So, mostly I use the path in both directions.
But here's the catch: Getting on and off the path in the "wrong" direction is crazy dangerous. In one direction, it means crossing three feet of deep sand and broken glass on a road bike. In the other direction, it means crossing a four-lane major road catty-corner-wise. So what I actually usually do is use part of the path, and get on and off it another way.
I guess what I'm trying to say in a whole lot of words is that like most things, it REALLY depends on the local situation, traffic, what's the road like, what's the path like, how safe is it to get on and off the path, etc., etc. Pictures might help...
Speed comes from what you put behind you. - Judi Ketteler