D,
You have some movement differences,316f vs regular 316, if everything written is true the 378 $ version should be top dog. But I would take that with a grain of salt.
We have a 50th ultimate version the ultimate supreme version (not to be confused with the 50th!) and of course the ultimate best version for a bit more, get the feeling someone is trying to sell you something. Maybe wait for the super duper 1-1 ultimate 50th supreme best version ever one due out soon!!!!
As far a serial numbers I have no idea nor would I care others for sure do they can chime in.