I'm putting my 4 string back in use because it's hard on the 5 string to jump massively between tunings.
I ordered a set of 55-120 strings for the 4 string, so now I can keep it in drop C, drop C#, and just leave my 5 string in normal BEADG and save the neck.
@LowEndMuse I don't tune down very often, maybe a drop D with the other strings at traditional tuning. At one show I had a separate bass tuned down 1/2 step because the singer was having trouble. 45-10 works well for me.