I run a Huck Norris in my rear tire only. It is substantially lighter than anything else out there, cheaper, and still offers rim protection. It won’t offer the same bead lock as cushcore but it helps some. My main concern was that if I run any less than about 32 psi in the back I ding my rim on roots and rocks. I’m able to run 28 psi now with no issues or dings or tire burps. I also weight 265 lbs and if I drop the pressure any more than 28 the rear tire is just a wet noodle on climbs. I ran the rear at 25 psi with no issues other than I didn’t like the feeling but I didn’t feel my rim hit anything and although I thought the tire was going to come off it never did. I’m also running a relatively light Maxxis Highroller 2 tire with EXO casing, no DD or DH casings as the tires are too heavy, I realize with a stiffer casing I could probably run lower pressures but I’m not in need of any more rear tire grip.
@supercraig probably has a little more in-depth info on the Huch Norris system as I got mine through him and Ironstone Cyclery. I was originally interested in the cush core but he countered with the lighter huck norris and since I am not Richie Rude the lighter weight insert made more sense, I may weigh more than Richie but I definitely don’t charge harder.