I don't think there is a breaking point - at least not if you're hosting commercial accounts (of any type). The risk of at-home power outages or overloads on your bandwidth far outweighs any benefits of converting from rental to at-home hosting. I know one of our major competitors lost power over this last weekend (12 hours) and we're fielding calls from their clients wanting to move here. Power outages will cause customer churn.

Only you can determine if the move would be financially feasible. We're not privy to your expenses or revenue. From a risk strategy, I don't ever foresee this a a good solution.