i have different strings on all of my basses (including rounds, flats, and groundwounds). you get used to switching back and forth
Kind of the same with me. Except I have different flats on both my basses... GHS for that old school thump and Chromes for that modern edge. I tried to go back to rounds a month ago - couldn't do it - no matter how much I like that "zing" rounds give when you do a fast slide down the neck. I just couldn't.

But yeah, flats are amazing. Like Jello, before Bill Cosby became a perv.