My point was that I'm just not sure that the research has, or hasn't, been done relating to tone, sustain and string gauge. Sustain would be fairly easy to study - you could hook up a steel with a .009, .010, .011, .012 and a .013" string, tune them all to the same pitch(s), hook it to a rack box with some kind of LED volume level display, and see which sustained longest (muting the others to eliminate sympathetic effects & adjusting for
initial output differences). Quite a few six-string players feel that lighter strings sustain
longer, once you adjust for the relative output differences, but again I don't know of any objective proof. I do suspect that finding "objective proof" for the common assertion that
"Heavier strings always sound better" could be a long time coming.
The stories about SRV's string gauges that "prove" tonal superiority tend to gloss over the fact that he tuned down a half step, equivalent to dropping at least a gauge, and he started each tour with .011's on there - equivalent to full-tuned .010's. (Those Dumbles were reputed to sound OK too). Stevie Ray could really work that squeaky microtonal stuff, but I don't consider him to be a really fluid bender in the way that Duane Allman or some of the better country guys are, with quick, inside bends against other held notes and in-tune multi-string bends. For what it's worth, I use .009's, .010's, .011's and .012's (and wound 3rds) at different times on different guitars, and they all sound...
different.... But for some strange reason, contrary to the ads in
Guitar Player magazine, NONE of them make me sound as good as Duane Allman
or SRV
or Johnny Hiland - maybe I need a better pick....