The tang used to attach the rack at the fork crown isn't strong enough to offer significant structural support. The angle between the force on the rack stanchions and the attachment tang at the crown still allows for flex in the fork. I shouldn't have said "zero", but it's not going to be a large enough difference to noticeably change the damping effect of the fork.

That said, P&S makes a really nice rack. If that's what you're after, then go for it.
If you're looking locally for an equivalent, ask Dan Boxer what a similar design would cost.