I wouldn't be without them. I've made the frames since I started bending wire. Hagen's sells the frames with and without blades and swivels, but as far as selling IMO there are just way to many out there to make any money on them.
The old flat living rubber had better action easier to tie better flare and was and all around better material in fine regular & heavy grade.
Old school flat rubber is just a spin off of the true flat rubber of years ago. Not made with the same quality grade material.
Round rubber is a good product in fine regular & heavy grades. It works well with silicone flashabou and bucktail accents.