I like this solution and am definitely tempted to give it a go.

Anyone got any thoughts on the best way to do this on a page with personalisation? (and this is really simple personalisation - one section of the page changes depending on whether you're logged in or not).

My solution would probably be to have the personalised section load as an async request but then you'd need to make sure that the async request can handle the same load as the microcached content.

Any other ideas?