I've been using this waist belt for a few sessions now and have been very happy with it. There are two things I've noticed about the design that are nice.
First is the width of the belt strap. The strap is super wide so I've found that when you get a good pull by wing in the surf, the belt doesn't cut into you as much and its noticeably more comfortable than other belts that are thinner.
Main thing I like is the bungee cord though. Its thicker and has more elastic range than my previous waist leash. My old one worked great but very often when getting up onto the board to begin a water start, I would get the line under my knees or wrapped around me somehow and have to straighten it out. This Core bungee design doesn't seem to do that. The "unstretched" length is short enough that there isn't excess line floating around to get tangled in, but the "stretched" length is plenty long enough to reach the wing tips for flipping over the 5m wing when I've used that one.
One thing to note is that this is a leash for the Hand Wing, not designed as a board leash. It probably won't be able to hold the heavy force of the board, just like most Hand Wing leashes. The only thing I would love on this leash that it doesn't have is a quick release between the belt and the bungee, just in case things get weird and you get tangled up in leashes in the surf.