I've recently acquired another Spector (Forte 4) so I can leave it tuned for all the more recent Rock stuff that's in C. My other 4 has a D-Tuner for any Drop D stuff and my 6 covers any of the 5 and 6 string standard tuned stuff. I tuned my Forte to what I would call "C Standard" (C, F, Bb, Eb), keeping with normal 4ths across. However, I've noticed that many are tuning to what I would call "Drop C" (i.e. "D Standard": D, G, C, F with the D dropped to C, equaling C, G, C, F). I would imagine some, but not many, in E Standard drop their E all the way to C as the D-Tuner can do this ("Double Drop C"???). So just curious who's doing what: C Standard? Drop C? Double Drop C? Vote the Pole!
I always tune standard. I have a fiver right now in A Standard since my guitarist is in Drop A. It's a little mental exercise whenever I have to follow what he plays on any other string, and it's way easier to deal with five unique notes per string than having seven on one.