Right, Ken. Both have identical valving.
Formerly I thought in some applications B8 are also slightly stiffer, but at least in case
of the Mk.V and Mk.VI variants they aren't.
Yes, I'd recommend to go for B6 instead of the shortened B8 to achieve better traction
on rough roads.
With Eibach Pro, Sportline, VWR or VW DG spings no shortened rebound is required.