1.) Is a limitation of Google's crawlable Ajax proposal. That would probably not have occurred with a proper standards body. What sequence of events would have to happen to have that as an inbound URL? I sense some previous JavaScript would have to have failed to allow that scenario.
2.) The site is already paying this price by redirecting _escaped_fragment_ URLs, and the old clean style urls. All inbound links will have this problem, so you're only shifting some of the burden through this door instead of the others.
no, with google's proposal, the #! links are all from the site root, see Lifehacker and Twitter's implementation. So these ugly half and half URLs never exist, and you're not paying a double request price
ah you're right, and yes that could possibly introduce the issue of redundant work done on the server depending on the implementation. However the two major implementations I've seen (Twitter and Lifehacker) use it from the root and so dont have that problem.
2.) The site is already paying this price by redirecting _escaped_fragment_ URLs, and the old clean style urls. All inbound links will have this problem, so you're only shifting some of the burden through this door instead of the others.