I have a G&L ASAT bass, a four string with a Tele body. People always tell me how cool it looks when I've played it out. But I had to add a custom made after market strap extender to make it comfortable to play.
Without that little device it had vicious neck-dive. That was in spite of having aluminum tuner posts. Even without the neck dive, the way the bass hangs, you have to have your hand about 3-4" further out from your body than you would with a P or J bass.
It seems to me that these problems would be compounded in a 5 string whether in-line or 4x1 on the headstock. You might end up with a really gorgeous, unique bass that you don't take out much because it's uncomfortable to play.