I think he means "height adjusted" so that the scuppers don't bare the brunt of the load. There should be 3 points of contact, and the blue noodle should take 1/3 or more of the total weight. (Too much - as with a TI, and the rod will snap)
No -the opposite in fact. The scuppers should bear all of the load on an AI. If any part of the hull bottom is loaded it will dent. A TI being so heavy can have problems so the hull should be more evenly supported - hence Hobie's new cradle cart. I am using a webbing strap on my modified Trax 2 TI cart. viewtopic.php?f=69&t=34910
The worst thing about the scupper cart is getting it back in after sailing. I have nearly finished a cradle type cart similar to sEs's (and now Hobie's new cart) which should make this easier.
The tennis balls spread the load evenly around the scupper tube base (which is the strongest part of the hull). I have wheeled both my AI and TI long distances and have had no problems. I am using half a tennis ball with half a sponge rubber ball inside it.
The three point rule is explained in a bit more detail hereviewtopic.php?f=11&t=38015&p=155216