I bought the Surf to Summit compact cart from REI and took if back.  I bought the Delux kayak cart and the kayak dolly from CLC and liked both. The bars that the kayak rests on with the delux are several inches farther apart, making the whole thing more stable than the compact cart.  The bars on the kayak dolly run fore and aft with the boat, and is even more stable than the delux.  So far, I have only used these with plastic boats.  Our usual portage is about 300' over a dirt road with some sand and uneven ground.  If your portage is short and over flat ground you would probably be happy with the compact cart.

Thanks! I appreciate your thoughts.

 Mark