Recently I managed to get my hands on some other Model Ms and was surprised to find that I preferred their key feel. The tactile feedback felt more precise, and the thunk of bottoming out was more authoritative and less plasticky.
Opened them up, all but 2 or 3 rivets were intact. Open up the SSK and see this:
![Image](http://img534.imageshack.us/img534/5093/20111016172307.jpg)
I have heard that the 84 key feels identical to the fullsized version, so would the loss of rivets be the source of the difference? I have not noticed any inconsistencies across the board and even in the areas where rivets are intact it feels quite different to the tenkeyed I tried.