I've seen or been involved with a few projects in the past few years that aimed to entice developers to work on premium domains in exchange for equity.

That rarely if ever works. Developers have too many gigs that pay them quite comfortably. If they wanted to make sacrifices, they'd probably expect to own and control the project.

You're better off hiring a developer for cash if you wish to run these sites as businesses. Otherwise, it makes more sense to sell them.