I dare say the majority of public Discourse forums deal in some kind of open product development. While we do support up-voting functionality similar to UserVoice with our Voting plugin, most communities don’t need it. Any product community that solicits feedback from users will commonly be practicing some form of complaint-driven development.
Discourse’s edge over UserVoice is that it’s a more holistic approach. In our model you don’t just put a spotlight on the “most wanted”, you also discuss anything that could work slightly better, is hard to understand or is straight up broken. And unlike vote-focused idea blurbs with drive-by comments, Discourse’s sustained discussions enable users & staffers to continuously hack away together at a crudely formed idea until they’re left with an informal specification.
You’ll see this pattern repeating itself in many of our feature discussions here on Meta.
Other notable communities excelling at open product development include:
Eve Tech
A device shop whose main selling point is that their products are designed by their community. They do employ Voting to a small extent, but the bigger story is that their entire forum is one giant roadmap discussion.
Soylent and Huel
https://discourse.soylent.com/
Two similar product lines with a similar product strategy: Let users talk about any experience, good and bad, and embrace the bad (not every body takes in a liquid meal with ease) with honest discussion rather than silencing it. Show me a focus group that would provide these companies with anywhere near the same amount of data and I’ll eat my 
EVE Online
It’s hard to make a pick among game forums as game makers are one of our biggest customer segments and they’ve been at the forefront of community-informed design for decades. Games lend themselves incredibly well to discussion about their rules, characters, aesthetic, balance, story, etcetera. A very common way of soliciting feedback from game testers is to silently watch the tester play your game and take notes. Afterwards you have a discussion about the play experience. An open forum is like that second part but scaled up 1000x.
In conclusion
You’ve probably heard this quote before:
If I had asked people what they wanted, they would have said faster horses.
~ Henry Ford
(according to legend, and that’s good enough)
This anecdote neatly encapsulates Discourse’s approach to open product development. You don’t arrive at a better design by pitting hundreds of features against each other in a vote-war. All of those features are parts of a greater whole. There’s only so much to be gained by having people shout their ideas at you. What you really want is meticulous discussions with a beginning, a middle and an end. You’re not always gonna get a happy ending, but if the story is good enough someone else will eventually tell it again, this time with a twist.