I did lambing season using one of those units and they are brilliant!! I could shift as required for fresh grass and I could usually foster a lamb and ewe in 12hrs though I kept them in it for 24hrs just to make sure. Bail the ewe for about 6hrs and then let the bail off, some ewes that would lower their back ends to sit and not let the lamb drink were kept up with a cord sling in the hip area. I had one of those units and some lambing pen/sheds but by far the unit was quicker and easier to use. My Grandfather used the bail system in a lambing shed and it worked well but not as quick as the outside unit. One lesson learned in that season was fostering in a wool shed is absolutely hopeless, or maybe it was because of the SNOW outside but I do not recommend a wool shed .
Don't get your knickers in a knot; it solves nothing and makes you walk funny.