I bought a Genesis 335S that came with the Crafted Grates, so over the past year have been buying the accessories and have bought the frame for my original Gen 1 Smokefire, just waiting for the actual Crafted Grill Grates for the Smokefire to be a more affordable price here in the UK, but still able to use the frame and accessories without them.
Accessories I have are Sear grate, Flat Top Plancha (best crafted grill level accessory imho), Basket, Pizza Stone (much better than the old bare Corderite one) Rotisserie basket and Skewer Set.
Think the Crafted setup is more suited to the Gas Grills Tbh, but the one that works best on my Smokefire is the Plancha, but it's easier to maintain high heat on the gas grill than the Smokefire with the lid open in my experience.
I'd certainly recommend the Crafted set up on the Gas Grills as a better buy than the GBS ones, as all the GBS accessories I have also fit within the circular part of the Crafted frame anyway, the Smokefire not so much, unless I was buying the Crafted setup already supplied with the Smokefire
As for the Sear grate it is a solid piece of cast iron and takes a lot to heat up, my Genesis gets to 900F+ with the sear station so it works well. The Smokefire at 600F although does heat it up, doesn't work as well as the Gas Grill because of the temp difference, I've found and isn't much difference over the GBS sear Grate except for size in the way it works on it.
If you reverse sear things like Tomahawks and Pichanas then the bigger sear grate is worth considering though