Re: low b string guage?
I still haven't tried them! Two reasons: I'm saving all my money for a bass, plus I need a trem post because one of mine is snapped. I cannot lower the action on one side, so until that gets sorted, there's no point in messing with this old RG750.
As for the tension, there's no way they will feel sloppy because the tension, according to the calculator, is 85 pounds -- exactly the same as a set of 9-42 tuned to concert pitch. The guitar should need little to no adjustments to the trem springs and no adjustments to the truss rod to compensate for a difference in tension. What would probably have to be reset is the intonation, that's all.