John, Offline IMAP use with UIDs for cache resynchronization was first mentioned in RFC 1733, which was published in December 1994. The concept may be older, but at least it's eight years old.
So, what are you suggesting, precisely? To me it sounds as if you want to break compatibility with eight years of RFC-mandated practice. A google search for 'imap offline' returns 29,000 hits, so it's quite a lot of practice, too. Have I misunderstood? --Arnt
