I've got a 2011 11" MBA that I'm in the process of replacing. Yesterday I purchased a new 2012 13" MBP (2.5ghz) along with the 27" Thunderbolt display. I decided to plug in the 11" MBA to the TB display in clamshell mode just to test it out while I was setting up the 13" MBP. I discovered that with the 11" MBA in clamshell mode running a few things like Safari (4-5 tabs), mail, and my Slingbox software in a small window (not full screen) the fan on the MBA started to go nuts. I just dealt with it while I set up the 13" MBP. Once I finished setting up the 13" MBP, there have been no issues with fan noise running multiple things at once (mail, Slingbox, multiple Safari tabs, iPhoto, iTunes, etc). This is what I'm looking for; it's great. Originally I went with the MBP because the HD is easily swappable and I dropped in a spare 120gb SSD I had as well as the RAM being easily upgradable. I knew the resolution would be lower than my 11" MBA and also much heavier. Now I'm having second thoughts. The higher res screen of the 13" MBA vs 13" MBP and significant weight reduction are starting to seem really attractive to me (maybe the 11" spoiled me). I'm actually now very interested in going with the 13" MBA upgraded to the 2.0ghz i7 and 8gb or RAM (possibly the 13" i5 upgraded to 8gb of RAM - technically don't need the 256gb SSD option). Here is my big concern - FAN NOISE when connected to the 27" TB display in clamshell mode! When I plugged in my 2011 11" MBA there was clearly significant fan noise under my normal usage conditions, which would make me crazy on a daily basis. Can anybody comment as to whether or not I would experience this same issue with the latest 13" MBA vs. my 2011 11" MBA? I plan to have the 13" connected to the TB display a significant amount of the time this machine is used (in clamshell mode) and also as a standard notebook as well. I'm not worried about the fan noise issue during normal notebook-type usage since I didn't have this issue with my 11". I'm just worried about when hooked up to the TB display. Thanks!