Okay - for people that buy for mechanics.
Does this mean that you use those mechanics outside of the published settings? And do you GM? Do you ever convert other settings to these mechanics?
For people that buy for setting.
Do you ever play that setting using other mechanics? Or do you only stick with the mechanics of that published setting.
What I'm trying to figure out here is this: There are a LOT of settings out there, and a LOT of game-systems. "D&D" has multiple versions of its system which supports various settings in their own way, but not everyone agrees on "which system" is best, but there is a "general" consensus on the better settings within D&D. Likewise, there are settings that a LOT of people like, Shadowrun, Torg, Rifts, that people constantly complain about the system, whenever these threads come up.
The heart of the question is - how many people WOULD mix-and-match their favorite mechanics to their favorite setting? Or do you stick with what is delivered?
Those of you that homebrew your settings, how often do you change mechanical systems? I don't mean tweak what you use, i'm talking major task-resolution changes. Moving from d20 to d100 or something, as an example.