My only concern would be the link rot that might occur if your urls are later rewritten to the new username. Which makes a mockery of having the vanity urls in

My only concern would be the link rot that might occur if your urls are later rewritten to the new username. Which makes a mockery of having the vanity urls in the first place. Having said that I can't even work out if a single Google+ post has it's own URI, or how I find it even.