I'm no expert but here are my thoughts.
Couple years ago we moved to the country and I got a whole bunch of chickens, some electric fence and a little chicken barn coop on wheels that I moved with my mower. I lost several to the hawks and vultures. I was so sad and discouraged I sold everything.
This spring I got the fever, but I wanted a safe way to keep the hens, but also wanted the benefits of free range lifestyle.
I came across chickenmobilestagecoach.com, and thought that really looked like the way to go for us.
We built two 4x8' tractors, modified the roost area (plans have a drop down floor, I wanted a solid floor) and modified the nest box (top opens and base folds down so I can clean inside the roost easily).
I topped them both off with a canvas tarp (very tough, should weather quite well vs a plain tarp) AND a sun-reflecting fabric (Leerburg Silver Shade Mesh tarp). The tractors are staying nice and "shady" even when they are parked out in the sun this way.
So I had the first tractor completed a couple weeks ago, and moved my 2 bantam pullets in there, and then completed the 2nd tractor this last week, and moved my 4 week old LF hens in there. So far so good. Definitely stands up to hawks (I don't think they can even see there are chickens in there because of the tarp/sun tarp). Also stood up to my 50 pound dog.
I can move them every day to every four days (depending on length/quality of the forage I park them on). The roosts are easy to clean, I use newspaper right now.
Like I said, totally new to the chicken tractor, but I think for my area with the hawks, vultures, foxes and coon problem, I think the tractors should be the right choice for us. And because the hens won't be left out I'm keeping it to 3-4 hens per tractor. Which is perfect, as we only need about 6 hens for our family anyway.
I liked this idea better than coop and pen, since the hens eat all the forage down to bare dirt and then stand around in poo, which means more work for you putting in some sort of substrate. I liked it better than my pastured poultry where I was doing great against land based predators, but losing too many to birds of prey.
Will keep an update over the year to see how it works out in the end. Especially winter, curious to see what we end up doing once the grass goes dormant.
