I'm pretty sure that R406a is a blend of two other refrigerants. The problem with this approach is that they have different characteristics and if you get a leak, one will leak out before the other. When this happens you have to blow the entire charge, evacuate and completely recharge witht the blend. There are also other considerations when charging like ensuring that you are charging in gas form to maintain the blend. If you charge with liquid you will only get one component of the blend and it will cause problems.
It may be better than sweating, but there are many service problems associated with it.