I made the switch from 4's to 5's about 20 years ago. At the time, it was out of necessity, almost every piece of gear I owned at the time had been stolen. All my basses and most of my rig. I didn't have the money to replace everything and I was still gigging. I went out and bought what I thought would cover the most ground and get me through until I could replace what I'd lost, a used head and a 5 string bass. I've been playing 5's ever since. I bought a really nice Spector Euro 4 several years ago. It had a spalted maple top(Like the Modulus 5 Sweetspot that was stolen in the aforementioned incident)and it sounded good...and it sat in it's gig bag for almost 2 years before I decided that it needed to go to someone who might actually play it. I may get another 4 one of these days, but it's not high on my list of things to do...
Maybe I'm one of the weird one's, because switching from 4's to 5's was a very easy and quick transition for me. Come to think of it, so was switching from "normal" to fanned-frets. I think I got my first Dingwall on a Wednesday, took it to practice on Thursday, and gigged with it that Saturday. Easy. I need to look into getting into 6's...
Maybe I'm one of the weird one's, because switching from 4's to 5's was a very easy and quick transition for me. Come to think of it, so was switching from "normal" to fanned-frets. I think I got my first Dingwall on a Wednesday, took it to practice on Thursday, and gigged with it that Saturday. Easy. I need to look into getting into 6's...