I've got a pretty killer 7 string now, and a few 5's, and a few 4's. I love the 7 , but for trying to play complicated slap lines, nothing beats a good old jazz bass for me. It's just a hell of a lot easier to play in my opinion.
Now, that being said, I definitely prefer having a lowB and a HighC minimum. I mean, I know Jaco and Vic both play(ed) 4 bangers, and can do things I can't do with 3 more strings, but I just love when my guitar player is hitting a heavy chunka chunka riff and I kick on the gritty, overdriven tube side of my mesa and hit the C and F for a lead like line. The even better part, is when he hits the lead and I go back to carrying the melodic rhythym again, which is my primary function, but it's still cool.
All my five strings are strung with High-C's, and I've been rolling that way for a few years, but now I'm thinking i'm in love with a 35" scale B string and have to get sixers to replace those five strings. The viscious cycle continues. I'll never go back unless I got a gig where they wanted a plain jane four string for the looks or whatnot, which I'd happily oblige. I mean, I just would have to travel more laterally instead of being able to play similar things without as much neck shifting. That to me is the biggest advantage of ERB's, less shifting up and down the neck.