Mike actually only has one walnut TBX (34" scale, 26 fret). The seldom played spare that you see on stage has a chechen top (34.5" scale, 24 fret). Here's Steve Lawson playing the chechen Q5 now owned by Mike:
That said, I don't disagree with his hoarding - If I had millions of dollars, I'd have a stable of TBXs too!
I actually saw this bass in person yesterday, it's very beautiful! It must have needed a factory setup