I can't say much more than a2. Roadies typically have a stiffer body position with 0 flow. The bikes fit soo big that they aren't using their legs in the same manner as a mtbiker. Body position is the key in mountain biking. Check out even the best xc guys and they have some body english, the best 'flow' riders have tonnes of body english, their bodies are bikes move like seperate machines but both work together.

Another key is your upperbody. A real trail gets rough and technical and you really need lots of upper body strength to maintain speed and flow through rough stuff. That ability to use the bike, upper and lower body all while pedalling is what makes it a difficult thing to master IF you want to maintain speed.

I think for the winter I will be getting a roadie or maybe a cx, I am hoping my ability to move on a bike will help with the fact I have very poor endurance ( know it won't )

BTW I thought you had a mtbike? I could have sworn you used to spend time in the mtb forum