In terms of playability I've always preferred a neck thru, in terms of tone I liked both. I've always found a neck thru to be less prone to dead spots but that could just be luck of the draw.
Now, I'm going to put my cynical hat on here and hypothesise that 'the sound is tighter' is code for it's cheaper to to build a bolt on. Vigier did the same thing, versions 1, 2 & 3 are neck thru, then along comes version 4 and it's a bolt on. A tone decision or a cost cutting one?