I would hope that the serial #'s are sequential... isn't that why they call it a "serial" #? hehe...
And which product started at 100? They couldn't of all started from 100...right? That means that some have a prefix to designate model or date. At least I hope it does.
Okay, here is my proposal!!!
Let's try and figure this out together! If you know for sure the approximate date when your (or any) piece of Mesa Boogie gear was manufactured (born, created, etc), then post it up along with model name, model # (if known), and serial #! Then after we figure this out, we will now have a sort of database to which to base our serial #'s on! And possibly even find an explanation to the numbering.
*hoping for no tumbleweeds or crickets*