I don't think it's so much about lighter. The sock requires a trip to the mast. You can't effectively raise or lower it with the sheet through a winch at the back. While some would argue it, the sock almost requires two people.
The top down furler, on the other hand, has more hardware, but provides a better degree of comfort, with the knowledge that you can put it away, right now, without needing to go forward.
Having had both, I found this kite to be in the lake a lot with the sock, and there was always a few minutes of messiness while the sheet got sorted out. With the furler, it's really fast.