I recently followed Kellers recommendation (Braised Short Ribs). It was fantastic. Really so. I will be repeating again soon. I've did it previously at about 140 for 72 hours as well, and it was also fantastic

I'd *think* that over 140 could run the risk of drying out (especially as you approach 68 C), but if it was served with a sauce or something, it might not matter. Also, with the shorter time, the danger of drying is reduced.