I use mysis-I'm pretty sure that its a heck of alot fattier than brine, but if you look at the water after you pour it off (I keep it in salt water in the fridge) its DISGUSTING plus, it may start to degrade, etc...
and, I think of it kinda this way: would I eat shrimp that has been sitting around in a fridge for a few days? a week... heck no!!! a day or two, leftovers, sure...