I suppose it's too late to fix it now, but this seems the best place to bring it up. I thought to upgrade my 9.0 installation to 9.1. I assume that I was asked at some point whether I wanted to do a fresh install or an upgrade, but if so it was sufficiently quiet that I missed it. I got a screen asking whether I wanted automatic partitioning, custom partitioning, or to keep my existing partitions. Thinking that keeping my existing partitions would be the only option compatible with an upgrade, I chose that. And without further adieu or even so much as a "by your leave", it formatted my lone partition. No confirmation dialog, no nothing. Having run cooker on my main machine for some time, I had high hopes for this release and expected better. Formatting partitions during install should be taken a little less lightly, I think.
Rocco