Reading this thread got me thinking about my Aria acoustic. Got it last year for use in the jazz band I play in. I've had a set of Status Hotwire stainless flats lying around that I got for one of my electrics a couple of years ago, and as an experiment I've just put them on the Aria. What a difference! Obviously the sound is a little brighter compared to the old strings (they were, dear reader, quite sh@gged) but because the gauge is lighter (40-100) than the old bronze ones, the tension on the neck is less and that means a lower action. I don't know what gauge the old ones were but they were very heavy and quite rough on the fingers. So, flats on acoustic bass is a goer as far as I'm concerned.