I had the rails some time ago with an 18" Silver. When I got the Performer, the baskets came with it and a big difference, at least for me. As has been said, you can move them around. I also have the sear grate and skillet so I use them for that. I load the baskets up with lump, light them for 5 minutes with the gas and let them go. Then I move both baskets directly under the grate. It gets the grate very hot and this is what I like for steaks, burgers and anything else I want to cook on "high direct". I wouldn't be able to for this with the older rails. For a regular "indirect", I usually bag them and push half the coals to one side and angled up.
Good Luck!