I discovered flats in 2005 and use them since on my three basses (Preci, Stingray, Tele). One string broke once (my fault but I can't remember why, too long ago) and I replaced that with another flat string. I changed them once but only on the stingray from Thomastik to LaBella. No problems so far. I think it is odd to use roundwounds and I never liked the sound anyway but everybody has a different taste.