Interesting! Can you share a bit on how you met this dev? Did you come up with this way of compensation upfront, or is it a deal you struck after some time working on it with him/her?
We made an initial call, I've pitched him several different structures of compensation and let him come up with a price for his app that he was happy with, then struck a deal the following day.
There's a few reasons the reason it got done so quickly, we both had worked with the same people within the niche.
I've also explained to him my strategy upfront to get the app back on the road, so that probably helped.
You just need to find the right match.