Hi, I've been a long time reader of these forums and finally decided to register so I can report this significant finding. First off, I've had several Cinema Displays in the past, including a 23" and a 24". Last year, I bought two 27" LED Cinema Displays to hook up to my 2010 Mac Pro and love them. I've grown impatient with waiting for the new Mac Pro's and decided to slowly convert to the new Thunderbolt ecosystem, with hopes that Apple will make Thunderbolt compatible with new Mac Pros (if they are refreshed). I've recently sold one of my 27" Cinema Displays and with that money I purchased a brand new Thunderbolt Display. So currently I have one 27" LED Display hooked up to my Mac Pro and one Thunderbolt Display hooked up to my 2011 MacBook Air. Since I've only had experience with this one Thunderbolt Display, this is by no means a scientific test, but I have noticed a couple differences in the 2 days I had with the Thunderbolt Display. - MacBook Air fans spin VERY loudly when watching videos on YouTube. I have never noticed the fans spin when it was hooked up to my LED Display (via USB and mini displayport). I have switched the MacBook between the 2 displays a few times, and after about 5 minutes, the fans will always be audible when it is connected via Thunderbolt. - The max brightness appears to be much brighter on my LED Display vs the Thunderbolt Display. I have no way of measuring this officially, but my eyes begin to strain when I max out the brightness on my LED display, which is a good thing because the ability to be bright is always welcome (whereas on my Thunderbolt Display, my eyes do not strain). Hopefully, Apple can release firmware updates to address the fan issue, but if Thunderbolt is associated with more energy transfer and thus heat, then fans do need to spin fast to protect the computer. The spinning fans make me wonder if the CPU, Ram, SSD will prematurely wear out when connected to the Thunderbolt Display (due to heat), also, is there unnecessary information being transferred through Thunderbolt to generate the extra heat? The lower max brightness is concerning, is Apple using cheaper parts now? It was my understanding that the LED panel should be the same, so I'm not sure why I'm noticing this or if it is just my unit. Please don't let me deter you from buying a Thunderbolt display, because it is very nice. Overall, you are not likely to notice the brightness issue unless you have both next to each other, but the fans are definitely noticeable and at this point, I'd rather hook up my MBA to my Cinema Display so the fans won't kick up. Hoping for some feedback or similar experiences.