True, Mac apps go through the Mac App Store (my mistake). But you still need to be a registered developer, as you mentioned, and that is the thing that tends to hold people back (the cost of it).
I did not know about gatekeeper. But I suspect many people don't either. I tend to try to leave my development and test machines in the 'vanilla' configuration that I expect my potential customers to have.
However, if you can instruct people you want to run your app on how to turn gatekeeper off, then you can distribute it to them.
But, IBOL, you still do need a Mac.
Hodgey, how did you create the .app file with Xcode without the provisioning certs and such? I'd like to be able to do that "just because I can".
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master