I totally agree with the concept. On terms of relative value, nothing will change. While "new btcs" might have a 1/10 of their actual value, everyone would have 10/1 btcs. It would make everyone's life easier, and perhaps provide us with the useful illusion of a higher volume.
Anyways, sooner or later we'll need to do something like this. Oh, and I don't agree with changing the terminology. We could just make big announcements stating that from xx/xx/xxxx 1 BTC equal 10 new BTCs, then, modify the old bitcoin client, and that's it. I think we should take care of putting enough emphasis on "big announcements": This should be announced at least 1 month before the actual modification.
My two cents.