I'm looking for options in the same quest, of a narrow nut measurement like on my Ibanez SR 600NTF ( [Invalid or Expired Link Removed] ).
I've noticed that Hofner bass guitars have extremely narrow necks ( Invalid Link Removed ), but they don't float my boat. I'm still looking, only because as much as I love my Ibanez, I find their shape and overall options for body shape and look to be boring. I do love the Ibanez Grooveline bass ( [Invalid or Expired Link Removed] ). That is a beautiful instrument, but currently out of my budget. I've owned two in the past and have to say they are the most comfortable bass I've ever played. I'd love to own one again.
Things I look for though, are more than just narrow nut width. I prefer an unfinished neck (no clear coat) and 24 frets (incidentally the Grooveline only has 22 frets, but it's still a fave with me).