My understanding of this situation is somewhat limited, but as I understand it it is OK to attend the SSPX Mass, IF and only IF you do not adhere to their I guess, philosophy, for lack of a better word. I have also heard that it is reccomended that people NOT attend them regularly as by doing so you may be drawn into their belief system.
Now I could be all wrong on that, but those seem to be the guiding principles.
That being said, and understand I am a hard core traditionalist, Rad Trad as it were, and I would never attend a SSPX Mass. I have had the opportunity to attend, on a daily basis I might add and did not. If there is an Indult I will attend that for Sunday and Holy days, and Novus Ordo during the week or if no indult is available.
While I empathize with the SSPX in many areas and think they are sincere in what they believe, we cannot create our own church. True the Church is in a terrible, terrible state these days, but we cannot ever hope to have things better by abandoning our belief in the Holy Catholic Church, and disregarding the will of the Holy Father.
While it is true that the Holy Spirit will never allow the Church to disintegrate completely, I do think that we are being tested, severly tested too I might add, and it is up to us to make things right, to stand firm in the faith and not give up. The early martyrs were prepared to and often did die for the faith. We should be willing to do no less…
COR JESU SACRATISSIMUM MISERERE NOBIS