I will never vote 3rd party again. (I have done it several times). I think it ruins a ‘pretty good’ choice and puts in a VERY BAD choice. The Republic is too fragile to risk that, ever.
I'd go with Webb unless there's a viable 3rd part alternative. Why? From everything I've read (granted, not all that much) he's a decent man. Jeb and Christie and anyone who backstabbed the conservative base are not.
My thinking is based on a kind of modified Hobson’s choice of taking neither bad option and defaulting to none in the form of a third party choice. The likely outcome (Bush or Webb) would be meaningless in terms of what I really wanted so the third party chocie would seem to be a logical civic action.