The new hatch from Hobie is said to be easier to use and more water resistant. I ordered the 8 inch version a couple of weeks ago to replace the center hatch on my Adventure. The new seal is an angled gasket installed on the door, not the base. The single handle is lifted then turned as the screw. This forces the seal to press out into the base as the hatch and base dock. The old hatch had six fasteners while the new one has eight. This results in a different bolt pattern for 8-inch hatch. The smaller hatch (six inch I think) is said to have the same pattern as the one it replaces. Here are the pics:
Old hatch closed
Old hatch open
New hatch closed
New hatch open
A longer view of the new hatch
kyt