I have not really read the marriage sspx deal with rome details. When you hear it from the sspx angle, it doesn't sound that bad. But, if you listen from the NO angle, it does. This guy from catholic answers minute 1:45 says that the ordinary witness is a priest from the NO diocese. And, if one is not available, the NO bishop should grant the sspx priest faculties to be a witness. That sounds like a bad deal if you ask me. Like I said, I have not read the details, but that doesn't sound acceptable if that is the case. But, with everything coming out of rome, there is probably language that says the contrary. And, also, this catholicanswers guy talks about how you can fulfill your sunday obligation at an sspx mass if you only go there out of love for the latin mass, but not out of love for the dissent of vatican 2. Basically, "yeah you can go to the sspx without sin if you are going to be a traditional modernist while there". But, if you are doctrinal traditionalist, you cannot fulfill you sunday obligation at an sspx mass.