I can’t tell you if they are really the stiffest soft boot out there but, they are stiff and I found the 08s to be very comfortable, lightweight and extremely warm. The REI store told me they are the stiffest boot they offered in 08. The Vibram sole is really nice and the aggressive tired provides excellent traction, which can be handy if you need to do some hiking. I am not crazy about the speed lacing system and would prefer traditional laces but, it works fine and does save time.
Funny… I’m heading in the opposite direction. I used my Drivers last year to cave (with some success in the right conditions) on a Palmer Honeycomb AM. I’m currently acquiring alpine gear and hope to ride hard boots exclusively (or close to it) this season.
<O:p
Good luck with your boot research. I think the Driver X is worth at least trying on.<O:p