I'm now on Recon and Scruff. No hits so far, but I do have a few positive things to say about the latter: you can sideload the app, the UI is slick (but at times confusing; still haven't used the "woof" feature afaik), the boys on there are slightly more attractive than the Recon users, there are more of them, and there are trans people. One thing I noticed is that at least half of the guys here really like their facial hair. I know there's supposedly a gene that triggers that attraction, but I can't personally relate.
Woof is like tapping on Grindr. Kind of an informal "hey, what's up" or "I find you attractive" with no expectation of a response. Agreed scruff isn't a huge population compared to some apps but they're pretty cute and willing to have a chat instead of hooking up right away.