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I put one on my Epiphone SG, but like you I was doing it at the same time as replacing the awful vintage style tuners. I suspect improvements were down to the new pegs, not the butler, but stability did improve.
Next time I change strings I’ll be taking it off to see if it was worth it. Shallower headstock angle on Epiphones is why I suspect it won’t make much difference. May be different on Gibsons.
I've almost pulled the trigger on a String Butler soooo many times... Not sure if snake oil but some people say good things about them...
I need to change the tuners on my Custom so may get one and install it at the same time the new pegs go on...