I know the 18" light is only .650" under the handguard, so it's very light. I have a Lilja with MLGS that is .650" under the guards, and it's 1lb 13oz, so the RLGS 18" JP will be as light or lighter.
Their medium contour is .650", then .936", then .875", and I have owned a .223 Wylde with that profile. I think it was ~2lbs. That barrel had been used for tons of high volume shooting by its original owner. I built a rifle out of it with a carbon fiber handguard, matched it with an Aero Precision upper, and it shoots .25 MOA at 100yds for 5rds. I bartered it for help from a friend of mine who did my reloading room/workbench, and his daughter is printing those groups with it. He's more than tickled with it.
We often hear that the Cryogenic treatment is snake oil, but I really don't think JP wastes his money and effort in anything snake oil related. The fact that .223 Wylde barrel has kept its accuracy life for so long makes me lean towards something in the sauce with Cryo.