Configurable everything = "hey i have a great idea, instead of designing a mod, let's make the users design it for us!"
Except that 99.999999999% of users won't even notice it's a config option. And you still need a default (which that 99.999999999% will use).
Inserting from the top *does* make sense...
what happens if your poll results in an even split between the two options?
if not in a config file, maybe a mode button on the machine?