As mentioned in other threads, the scale length is the killer. A low E or drop D is about as far as you can get on a 25 1/2" scale before its too short. So yes, keeping the B string fresh will always help, but what I find is that some string makers have a larger core and smaller windings to make the exact same string size. I think that's a better fit than a smaller core and fatter windings. When the windings are too fat, the string is under less tension and the windings tend to choke off the vibrations. I don't know how you tell which brand is which, but it might be time to experiment, or start opening packages at the store and compare winding sizes.