I am still testing a new build with the 900, and the 180 was my other choice as well. I am building it for a friend who told me to build for him what I would build for myself, but that he did not want a huge case, so I chose the 900 purely because it is smaller than the 180.
One thing I really like about the 900 that has not been mentioned so far is that cable routing is an absolute dream. I obsess on things like cable length and placement, and never feel like I've gotten remotely close to clean enough. In my last build for myself, I even had Performance PCs fabricate some custom length modular power cables for my OCZ PSU. Even after all that, my last build was just OK on the neatness front.
The 900 comes clean almost without trying. The PSU in the bottom leads to a logical path for the 24 pin cable. Of course, the fact that my HD and optical drives are all SATA does not hurt, either.
Anyway, my OC efforts on this E4300 in a 965P-DS3 are getting into the warm range, and I have just switched the fans from low, where they were not particularly noticeable, to medium where they are very noticeable. I shudder to think what high might sound like. Then again, my load temps dropped by at least 3C when I jacked up the vots to the fans.