One vs Two Piece Axle? After finding out my bike has a road rear (130 mm) &amp; disc brakes, it's been difficult to source rear hubs.  Cyclocross allows disc brakes, and more commuter/cx frames are appearing but all seem to use the 135 mm spacing...  Chris King's Universal Disc rear tandem has a 130 mm option, but as a two piece axle?

Could someone explain the difference, and provide pros/cons?
If you have a steel bike, a good shop can "cold set" it to 135 mm.

This PDF on the Chris King website illustrates the 2-piece axle.