I am in a similar situation, I just found a number of southern dewberries (member of the blackberry / raspberry family, think thin vine like blackberry covered in millions of hairy prickles vs thicker canes, and hundreds of individual thorns with blackberries) growing in a hedge yesterday, and picked about a quart of berries, all growing at about shoulder level on the top of the hedge. I plan to leave them as they are a couple of hundred feet from my thornless blackberries. There is probably another 3-4 quarts of berries are still red on the dew berry vines, so they will make a nice preview of blackberry season, though I do hate all those thorns. (Southern Dewberries ripen about a 3-4 weeks ahead of blackberries)

I've had wild black raspberries in poor settings that were still quite productive, but they grew so aggressively and they'd throw out long canes full of nasty thorns that would root wherever they touched. I cut them out -- it took a few years and I still need to watch for them. lol! I stick to growing only thornless berries now. :)

How much fruit they produce is dependent on many factors, could be amazing or mediocre. My parents had an amazingly productive bush when I was little, however they didn't like the thorns either....

For what it's worth, I'm going to entertain the wild black raspberry that I found growing at our new house. It overwintered much better than the "Jewel" variety that I planted last year. Might be something to keep in mind, especially since you're in a zone similar to me.

Thanks everyone. I’ve been reading about black raspberries and it looks like it’s recommended to prune them back to encourage side branches. I may try that to see if it makes for more berries.