When I cook meat at low temps the meat seems to lose a lot of the moisture. A steak cooked at 56C for 3 hours is a bit dry, especially when compared to one which is cooked at 53C for the same period.
This seems to be even more problematic when cooking for days. I once cooked brisket for 72 hours at 58C. The meat was very tough and chevy - basically unedible - and had lost lots of the moisture as well. I am wondering if I am doing something wrong. I have not succeeded to tenderize tough cuts at low temperatures, and they have not been very moist either.
So far I've got best results with naturally tender cuts, or if I use tough cuts I just overcook them at 80C.