Ian, funny, learning play bass has taken me away from really building (except I'm building my own bass) for the past year. I've seen and played the u-bass, and have only seen KonaBob's creation when I wasn't interested in bass (at the time).
I went online to view the concept behind the WalkingBass, and if I had never taken bass lessons before, and wanted to get into playing bass, I'd get it. For Hawaiian music, the WalkingBass can lay a very good groove - I've heard KonaBob a few years back, very nice. Of course, so can the Kala, but I prefer Owen Holt's solid body version for something in that scale length. Unfortunately, I think I'd miss the extra 4th string, especially since the guy I play with is all over the map with Gabby and Peter Moon stuff - I always sang their songs, but never noticed what it took to actually play their music, ie: How d'ya do, Flying, Kauai Beauty, Pua Lilia, et al.
Of course, no excuses from me, I just prefer more custom stuff, rather than off the shelf. But, if everything was off the shelf, I'd enjoy playing the WalkingBass more than the Kala, just because. And therein lies why I like custom stuff built for the player - if you're comfortable with your tools, and you LIKE playing them, the music you'll make will be that much better.
Personally, I'm in the final sanding stages of my neck-through P&J. I'll post that later I'm sure.
Aaron