I also use "hoop coops" made from cattle panels. These work better in the hot summer temps than the Salatin tractors, because they are a lot more airy.
I was looking at those also. Since you have built both, which one do you prefer? The only reasons I could think of for not using the hoop coop was a possibility of it flipping over in high wind and the need to build a door as opposed to a hatch. I know the last one sounds lazy but hey, I've had to build a lot this year and I was looking to cut some time off my to-do list. and I'm all for work smart not hard.