|Recently did 7000km over 3months towing a large blacktop van. We got the isi as it was rated at 6.5G (correct me if I am wrong) after seeing so many broken bike carriers from the back of vans. Up, down and rotational forces put about 3G at the back of a large van. We moved it from the back of the van to car quite a few times each week as we moved around looking for mtb tracks.
it just works so easily and is tough... it is a piece of 4wd equipment. It is easy and quick to transfer once you get the knack of locating the locking plate and loading bikes is quick.
Put the bikes on and forget. Money well spent!