This is probably better to take to the sous vide thread, but:
The main benefit is being to decouple "doneness" with "done." (Defining "done" as safe to eat from a pathogen standpoint. Defining "doneness" as being cooked to where we like it from a taste/texture "good food to eat" standpoint.) Adding cook time, especially on tougher cuts, can be tricky to do without drying them out in conventional cooking. The meat is "done" at 120 or 140 or whatever based on the pathogen time chart, but in the case of a shank or a cheek or a brisket or pork shoulder, it is not at a tenderness level where anyone would want to eat it. At that point, you just need time to break down connective tissues. If you go hotter, it cooks faster, but you dry out the meat more or get a meat texture that maybe you don't like. Think of traditional methods like braising and confit, that's basically a sous vide environment prior to having the easy control of sous vide. Those methods try to immerse the food in a moist/fat environment to reduce moisture loss - sous vide doesn't require it because it never heats the protein to the point of losing the moisture in the first place.
Sous vide give you a very reliable way to control temp and time independently, so you can get the meat "done" and then carry it to your desired "doneness."
There really is no risk, within reason. Understand the pathogen time/temp chart - the lower the temp, the longer it takes to make food safe to eat. Conventional cooking happens quickly and hot, so the required temp is high - hence the FDA cooking temp recommendations that result in dry pork chops and chicken breasts. But if you use a lower temp, longer cook, you never dry out the meat, you never tighten up the proteins, yet you still render it safe to eat. As a general rule, longer is always safer as it kills more and more pathogens (unless you are so low in temp that you are incubating the pathogens):
(Chart stolen from culinaryreviewer.com)