True to my user name, grew up on east coast and will still say that after many years of a variety of endurance sports I have never done anything harder than racing off-road enduros on the East Coast of US; Maryland, Pennsylvania, Connecticut, and New Jersey.
Former off road Katoom convert for motard and recently sold sport touring (VFR). I think I am on the verge of owning as many bikes as motorcycles over the years. Started on a GT80 (4-up) and I think I have had just about every major brand save a Harley.
I miss off roading very much, but SoCal is not the place for this (not into desert) as I grew up surrounded by single track woods.
IMO, in terms of triathlon lots of carry-over in bike handling, especially descending, and mental toughness in longer events from years of riding.
Thanks for stirring some very good and sometimes "painful" memories!