I dont know if its exactly the same as his methods, per se, but yes, i have used a chicken tractor before. since it wasnt very big (~4' by 8') we used it mostly as an adjunct to our main coop, mostly for raising young birds separately, finishing fryer/roaster cockerels where they wouldnt make a nuisance of themselves, and "testing" older hens to determine whos laying. it was built of pvc hoop and scrap wood with chicken wire and plastic covering, with roosts, a small laying box, and a platform holding the waterer. we mostly ran it through old beds in the vegetable fields, but sometimes on grass or leaf litter under fruit trees. it was moved by hand, typically daily. we plan to build something similar againsoon for similar purposes. portable foldpens are handy sometimes esp for running over garden beds, but their small size and rigid shape can make them less flexible than portable fencing--just depends on the situation.
we have neither predator problems nor cold winters so i cant speak to either of those...
we use something similar for finishing meat rabbits--also with no bottom (they do not dig out). it has wire sides but a more enclosed area they can shelter or hide in at one end and a flat metal roof. It may have even more practical value for rabbits since they are herbivores. it gets moved once or twice a day depending on stocking density and size of bunnies, and once they adjust they can eat a lot of grass and weeds, making less work for us gathering forage, tho they still get pellets and other supplementary feeds and usually grow a little slower, tho they do get more excercise and enjoy an more "natural" environment.
they can be a useful tool in the right cases. hope that helps...
