Obvious changes: the cabin is gone, and in its place is a neat wrap-around coaming (which has the added advantage of stiffening the deck in place of the missing cabin sides), note also the tiller modification and longer seating.

A very clean modification and it looks to be a fun boat to sail.
Interestingly, open-decked Weekenders like this one and the one we built in Hawaii (that boat had a removable cabin) led us to enlarge the Skipjack into the Super Skipjack we now have plans for. I can certainly see the appeal of the open boats for sporting around, but—at least for us—we think there's a strong appeal to the cabin, both visually and for its coziness!