If nothing else, it's a cheap experiment to go buy several gauges of the same string and see if you can hear a difference. I'd say it'd be best to record the demos and be able to some how blind shuffle them (and have us vote!) on which one sounds the best. Although, I'm thinking the tiny difference may be tough to discern with a recording.
I will say in regards to SRV (and Jimi's) sound that drop tuning makes a bigger difference in sound than changing the gauge of strings, imho.