Tried it for a few months, but only with an octave down pedal. Used a 2x15 mesa rig. Soundwise, bit like a fart in a wind tunnel. Never really sat well in a mix with seven and eight string guitars, even when properly mixed live or in a studio.
That's my experience w/ drop and octave pedals, that's why i opted for a 6 string tuned to drop E (EAEADG) it's night and day honestly. And it sits way better in the mix IME because you can actually EQ it correctly (or so it feels). My tone is one of the best I've heard and a normal bass E sounds thin to me now, it's like my new D string lol. People love how heavy and low my bass can get though, I only get compliments and bewilderment haha