I honestly don't know if I'd go or not if Fr. Pfeiffer were my only option.
If you're looking for in-and-out sacraments, the FSSP and SSPX are probably safer options.
If NO ordinations/concecrations are doubtful, then FSSP is not an option. Their priests are ordained by bishops concecrated in the modern rite. Also, in what rite are their priests ordained? And if a priests comes to FSSP from straight up NO, I'm sure such priests aren't conditionally ordained.
As to Fr. Pfeiffer, if I understand schism correctly, it has a lot to do with one's relationships--relationship with the Church and/or relationship with schismatics. I have asked numerous times for somebody more knowledgeable to correct me if I'm wrong, but thus far I've only received basic affirmation.
Schismatics are only to be approached for the sacraments in danger of death. If I, one Sunday, willlie-nillie decide to go to Mass at a Greek Orthodox Church, then I would be in schism. I am not sure what would need to occur to shed schism once I realized my error (i.e. regular confession, bishop action, etc). But I'm quite certain that continuing to publicly defend my visit into schism and to argue that the Greek Orthodox aren't schismatic would retain me in schism. Now ponder Fr. Pfeiffer and the schismatic fraud.
Another action that places Fr. Pfeiffer in schism is his whimsically red-lighting other solid-teaching good valid priests. This says "don't mind your Sunday obligation and don't avail yourself to the sacraments because I'm having a playground temper tantrum against Bishops and Priests XY&Z." This is choosing his own ego over the Catholic Church; this is advising to ignore the Catholic Church (miss Mass, etc) and to stay away from the Catholic Church in favor of an ego, albeit a massive ego.
I have posted the crux of this several times and invited critique; this is what I earnestly and honestly believe; and until someone better versed in what constitutes "schism" straightens me out, then I would only turn to Fr. Pfeiffer in danger of death and in the absence of non-schismatic valid priests. And then only for the sacraments--not to attend one of his Masses sprinkled, if not laden, with schism spewed from the pulpit.