Well here in Ireland, I know of not one of our faithful who attends the SSPX anymore.
You can argue it is because of the situation here if you want, but the US and France are the only countries where Resistance faithful still think it is ok to attend the SSPX.
The reason for not attending is so simple. Look at St. Hermenegild. He refused the sacraments of a Bishop who was giving totally traditional sacraments. There was only one problem; he was Arian.
So by the same logic, the SSPX, who have put themselves under the authority of Rome for marriage, confessions, and so on, have become part of that modernist apparatus. While the individual priests may not be modernist (as is the case for many indult priests), as a matter of principle, nay more our very faith, we must refuse to receive their sacraments. The same applies for Orthodox priests and receiving their sacraments.
There seems to be a strange combination of human respect, fear of change etc. etc. on the part of priests and faithful for refusing to break with the SSPX. All we are doing is following the example given by the SSPX of old, when it comes to attendance of pseudo traditional Masses.