Pins are no longer limited and the market is definitely saturated so it is foolish to preorder IMO. WoZ is a great example. No benefit whatsoever to preording it. Now you can get them for basically the same money and didn't have to wait 2-3 years. Plus most of the bugs worked out. Of course I was telling everyone that 2 years ago...
MMR will be the same way. The smart thing to do will be to wait. Play it and if you really want it buy an HUO and save a grand.
If someone actually makes a LIMITED pin in the future (200-300 max) then preordering is fine otherwise wait.