I guess it depends what your bottom note needs to be.
I like having a low D (low blue 7th if you're in E), so I experimented with DGCFBb for a while (i.e. tuned down a full tone from EADGC). Too much like hard work at the time, because I needed EADG tuning for something else, and trying to know both at once did my head in. If I was starting from scratch, or going purely to 5-string, I might try that route again. As it is, I have given up fives almost entirely.
Either way, I'd be very reluctant to shift away from constant interval tuning.