a wreck is a wreck.... but also take into consideration that they are made for different things. everything wrecks hard. but what you choose to do with them is what makes you wreck.
for instance- my hydroplaning wreck. without the quad i would have never chosen to travel 30-35 feet across a pond. stupid yes, but possible indeed so.
bike- not doing it unless im filming for nitro circus five. considered insane by many on two wheels, where jumping 150 gaps is cake for bike riders with real experience. thats insane!! if you have seen akraix 2, then you know ben bettis almost ate **** the first time he went for that gap. a bike would have been different. if the bike came up short like he did, no axle was breaking.... just a nice throwing of your body over the bars and HELLLLOOOOOO rebound, so to say quads wreck harder is just an out to minor spills where weight is really an issue.
bottom line- any powersport is dangerous. thats why we do it. if your concerned about wrecking then dont do something. BOTH are equal!!!!
if you fall its because you couldnt make something happen regardless of what your on-bike or quad. it is simply a matter of rider and how they position themselves to make something happen.
as far as skill- bikes need the mastering a quad might not. for wheels rolls without lean. two wheels is obviously a little harder. this is the difference- skill level. not how hard they can wreck.
-ant