yeah ,It has super comfortable neck .
I have narrow option for 5 string neck because most brands has crazy neck that are unplayable for me .(my label has a sadowsky and I can not even play it or same for fender basses ).
I should repair it (6th time this bass go for repair ) which is kind of weird because a lot of Yamaha bb415 owner are so happy and never face a problem but mine started with broken nut then broken toggle switch and the electronic problem and now input jack and a dead pickup .[/QUOTE]
Actually some brands do it crazily ,I mean fender 5 string neck is huge.Some brands like yamaha or Ibanez do this in a good way but some high quality ones make Big and chubby necks and they do not fit at all .
I do not know why but that is kind of shocking .
Odd, all those issues you have had with the Yamaha. I have owned a couple over the years (BX4, and BX-5, both a bit different for Yamaha, being headless basses). Their neck were, actually, too narrow, but I got used to them; the BX-5 was my first 5 string bass I ever owned, I got it in 1987, so there wasn't much available in the 5 string market at that time.
Fender, and Fender derived, 5 string basses do have huge necks, especially so as you go up the neck towards the body. I would have bought a Roscoe Beck bass, except for that.
I have both 4 and 5 string basses and comfortably switch back and forth, but, I have been doing so for over 30 years now; in the early days, it did trip me up occasionally, but that was probably due to my sticking one or the other for extended periods of time. Alternating playing them daily is what makes it easy, now.
Even though you have problems with the BB415, you can still use it to practice with and, try the idea of using the B string more as a means of greater range from the low E note and up for easier facility with string crossing to higher notes, rather than just looking at the B string for those few extra low notes. Plus, the sound of the B string, even higher up the neck, is fatter sounding, something I make use of for tonal reasons.