OK. I just had a crack at trying to upgrade - and sure enough lots of things work a bit differently. The end result appears to mean that my site will need quite a bit of work to get it to run under RefineryCMS 2.1. I'm sure you guys know about most of these issues so I'm thinking I'll probably just wait for the documentation and save myself a bunch of time poking round the source of the new release. FWIW, after fixing a few things, it looks like the blog engine is going to give me the most grief with the upgrade.
I am really hoping the (cacheable) menu Presenter stuff ramps up my production
performance since rendering the menus for every page seems to take well
over 50% of the server time under refinery 2.0.10.
Thanks for your hard work and I look forward to the full release with documentation