I have never had a problem with braking strings. I have a Gibson LP and a Ibanez with their own floating bridge and i haven't broken a string in 7 years. I've used XL, GHS, Fender and Ernie Ball with mostly nickle and tried stainless a few times. The cobalt's, Sonicly, seem to have more attack and output, which i really liked but the alloy seems to be very hard, so the string brakes ALOT more easily. I do not rekommend these strings if you can't live with a more fragile string ! I you have a tremolo that you what to use, forget it. If you are playing live, forget it. If you are recording in a studio or using at home, keep two sets at hand for when you brake strings. I want to add that the strings broke not from actual playing but from loosning and tightning the string when tuning.