No one can say that EVERY new mass is valid, nor that EVERY one is invalid. But the evidence leads one to say that most are invalid. It just depends on the "priest" (if he is one), it depends on the canon prayer used, and it depends on the "priest's" person intention and his proper seminary training to have an orthodox understanding of the mass.
Just look at the english speaking world: +Benedict changed the consecration phrase back to "for many" from the invalid "for all". He said that "for all" was invalid. How long was that used in America and the english speaking world? 40 years! From 1970 to around 2005 or so! Every single new mass said with "for all" was 100% invalid. And there are so many other reasons for its invalidity, apart from this clear one.
Cardinal +Ottaviani, one of the top theologians in rome in the 60s, said that, based on how the new canon prayers were written, the new mass' consecration "could be positively doubted" as valid. Nothing has changed, theologically, to make the new mass less doubtful. In fact, with the added issue of doubtful priests, the new mass is MORE doubtful than 30-40 yrs ago, when at least the priests saying it were true priests.
So, the point being, the sspx's opinion on the matter is unnecessary and irrelevant. Cardinals +Ottaviani, +Bacci and team had more theological training than the entire history of sspx priests (500+) put together. There is no reason for the sspx to "re-invent the wheel" and examine an issue that has already been decided. The new mass has many "positive doubts" and the doubt has only gotten worse with time.