[tw04]

No, sooner or later an exec swoops in with "this is our largest customer!!!!". It's still a P1, it just gets bumped to the front of the line - because revenue. Nothing wrong with that, and no need for a different numbering system. Their P1 is no different than a smaller customers P1. They just get to be first in line because they pay to play.

[douche]

Or what is even more likely, in my experience, "this could be our largest customer!!!!"

Sales-driven-development is lots and lots of fun.