I was wondering what the primary differences are between a X-Terra 70 and the newer model 705? I bought my mom a X-Terra 70 about three years ago and now that she has grown comfortable with it I am wondering if it is worth considering the newer model. She has the 5x10 18.5, the 6" 18.5; the 9" 10.5 and the 10" 18.5 DD. The 705 seems to use all of these coils from what I can tell but I was wondering what the members here thought of the two systems.