<font color="green">RickS, Just remember.... a heavier tiller on the rear means more counterbalancing weight will be needed on the front if you don't want to loose too much steering ability or front wheel drive.
Depending on the frequency of tilling, size of area(s) to be tilled, and soil composition - the first tiller may suit your needs just fine on your size tractor. The second tiller is certainly sturdier than the XB model to which you linked in your first post.
Mike </font>