Yeah, I'm thinking it would make sense to use medium gauge strings for tuning down.   

Walt Robertson's trick wouldn't have worked on me, because it takes me a couple of seconds to figure out what key the guy is in, by finding the right lead pattern, and then I can play along with ease no matter what key he's in. His only hope would have been to tune "in between" the normal notes halfway...or else just ask me please not to play along. The direct route is usually the best. :-)

- LH