Of course you can use the scupper cart to transport your TI to the water, how else would you do it???.
I think what Hobie just wants everyone be very aware that because of the weight of the TI a standard scupper cart (like used on all their other boats) is no longer recommended without additional means of support.
The fix is to purchase the Hobie contoured cradle for the TI (you can get it here http://www.austinkayak.com/products/130 ... radle.html
, or build your own with the same design (that's what I did) in order to transport the TI on a standard Hobie scupper cart (of course the cart has to be one of the ones that can carry 200 lbs). The cradle is in the catalog (near the scupper carts) It's around $30 bucks (very affordable). I have the HD card with the foam filled tires, and recommend that cart.
To be perfectly honest I have a much easier time transporting my TI with the AMA's removed (much easier to pull). I remove the AMA's and carry them separately down to the water, then put them on at the shore (they have nice carry handles and you can carry both together). I also have a cart with the grey air filled wheels (for sand) but seriously seldom use it. It takes much more effort to pull the boat with those air filled tires on everything except very soft dry (and deep) sand, then you thank your lucky stars you have the air filled wheels. For us that is less than 5% of the time that we need the air filled beach tires.
Typically I roll the boat off shore and out into waste deep water, put the rudder down install the mirage drives and remove the scupper cart. I store my scupper cart upside down in the rear scupper holes, I usually keep a spare life jacket back there, and the scupper cart and cradle sits on top of the life jacket (in the scupper holes), it's pretty much out of the way back there. If you have the air filled tires, you will notice that they are quite buoyant, I filled mine 1/3 full of water or slime (from walmart in the bike department) so they are easier to get under the boat in the water, though it does make the tires heavier, it's worth it in my opinion. Or you can do like Kayakingbob and tear the cart down and store in the front hatch (they tear down very quickly and easily).
We are out every weekend with our TI all year around, and always launch from beaches 99% of the time ( I don't like powerboat launches).
Obviously we live in Florida where it's always warm all year round, I don't know how the up north people do it when it's cold.
Hope this helps you