I went to the Sunroad Boat Show in San Diego this past weekend. There is a really nice J-124 for sale (was for sale last year too, lol). Anyway, the J had what I am 99.9% sure is Interlux Interdeck non-skid. I thought it looked great and the texture was just right, grippy but won't hurt bare feet. I do think you'd draw blood if you scuffed your knees on it though.
Anyway, since I'll be using Interlux primer on the decks I'll probably go with Interdeck. There is another forum member doing a restoration of the same boat as mine and he got Kiwi-Grip. Hopefully he will finish his decks before I do so I can check it out.