One reason I'm a big fan of my Yamaha TRBXs is their necks. Very comfortable for me, I don't like thick necks.
40mm on the trbx174, and 38mm (4-string) or 43mm (5-string) nut widths on the 600 series.
I find myself often going back to my four string because that's what the song was originally played on, but I think I'm going to try and adjust more to my five, for reasons already mentioned upthread. I'm still in the transition, myself, but enjoying it. It's nice to be able to switch back and forth, that's my vote. Have at least one of each