Figured these comments fit in this old thread. If you are off pavement wear the most protective boots you can get, period. It should be an MX boot.
My ride this morning was a mix of pavement and gravel and being cooler chose my Forma Adventure Tall boots over my O'Neal Rider MX boots. BIG mistake. Low sided coming out of a corner at low speed (I gave little bit too much throttle for the conditions), bike spun around as it came down on left side. It slid a bit on my ankle and broke my fibula.
I am certain with the O'Neal Rider MX boots I'd be fine, maybe would have tweaked my knee. I'm learning the hard way...if off pavement I'll be in a MX boot. Even comfort wise I don't see the O'neals as bad so quite frustrated with my choice of footwear this morning. Ugh.