Most community software would give people the option of G+, FB and LI identities, on top of regular email identity. I can't imagine the cost/hosting of something like buddypress or elgg would be all that burdensome, which would give you multiple social logins as well as keeping things in-house vs under google's control.

You're trying to go after a rather single-minded crowd (solo founders) and you may end up losing a fair amount of value from people that won't bend to your identity requirement.

I'm not a regular G+ user but I'd rather use G+ any day of the week over either BuddyPress or Elgg (because they're terrible) and I am certain that these guys have way better things to do with his time than write a better community portal. It is burdensome and it's presumptive of you to expect him to burn his time on something that benefits a tiny outlier of the audience. To be honest, I'd be less interested if it was populated with people who care that much about waving their Not Google+ flag because trivialities like that should be a very low priority for people in that solo-founder bucket.

Thanks, gregormck and crew! It's a great idea, I'm looking forward to seeing what comes of it. I'll be looking into it this evening.