my impressions... definitely not worth it. then again i tested it for about 30 minutes but here is what i did (on the 1.86 w/ ssd new model confirmed, it had 4 finger swipe). i started an ichat and youtube and just like my 1.6 80gb rev a it heated up. while the fan didnt rev up to 6200rpm it was still hot and lagged noticeably. the hulu.com test... ran hulu (episode of office) in hi-res, full screen and it was laggy just as on mine. verdict... I, at least, am not going to upgrade to the rev b as it seemed the performance was quite similar. While I usually like staying extremely current and having the latest and greatest, the new macbook air looks the same and performs the same... so I will not go out of my way to sell this machine and drop a few hundred for the same thing. Once again, this is MY impression and what I and doing, sorry if I offended anybody. I am just being honest and if you want your own opinion go test it for yourself, maybe you will feel something different. However if you ask me, I would definitely say it is not worth it to upgrade to a rev B.