I've found that Jazz necks can have the same dimensions on paper, but feel very different in real life. Nicest neck i've ever played was on a bog-standard late 90's Mex Jazz. Put any US models to shame. Personally I favour a thicker neck as I'm a fat bastard and hang my flabby left arm off the neck which changes the pitch too much on a slim neck. Tried playing a Geddy Lee once and it felt like the neck was all over the show.