Any luck at the Apple Store?
Glad you asked - Monitors In Motion suffers from a bit of a disconnect between their departments.
Even though they asked for customers to specify at the time of ordering if they have the late model 2012 iMac, the part they sent to connect to the back of the computer is incompatible - it's for the previous iMac model(s).
I called MIM and confirmed as much - when I looked closer at the pics on their Facebook page, the part that fits in the back of the iMac looked different from the one I was shipped - and they said over the phone that the part was a week or two away from being manufactured! Frustrating, to say the least - their marketing is ahead of their manufacturing, and if I would have known this I wouldn't have pulled the trigger when I did.
So my build-to-order iMac is sitting useless on the floor and so are the parts from MIM - and have been going on three weeks now, while I wait patiently for this promised part. Then, and only then, can I take it into the Apple store - where I can only hope I haven't been lied to again by MIM if the Apple store tells me "no can do." We shall see...