Let's not forget...Tony Iommi tuned down to either Eb or C#, the boys in Aerosmith also tone down quite a bit...E or D, Billy Gibbons has been tuning down qlot lately...either to D or C or B or A, and I mean all the way doen (all 6 strings...with 8 guage strings no less!!!)
used to play at Eb, but i tuned up and liked the harmonics and chimier tone much better.
There's a reason why standard is STANDARD...it's what the guitar was designed to play it's best at. I'm sure you can set up this, and string gauge that, but i can assure you that good old 10's at standard tuning will sound great on any decent guitar.
EVH did infact tune down to D on the 1980 "Invasion" tour promoting "Women And Children First" . In 1982 he started tuning standard for most of the tunes in the set though on occasion the band would tune a half step down. From 1984 to 1993 he tuned standard , 1995 a half step down , 1998 standard tuning , 2004 a hlaf step down. I know , I need to get out of the house more!
I wasn't aware of the live stuff, although I do know he was standard on the F.U.C.K tour and down half for Balance. I was just going off the studio recordings.