They rejected papal infallibility. We reject not a single dogma of faith. No comparison. And I don't accept that the SSPX is schismatic. It does not reject the papacy. That is the Pope's idea--but it's strictly unilateral. The last I heard, he can't make somebody something he isn't. He can't claim someone is a schismatic who is not a schismatic. Oh, sure, he can say it--and even deal out some punishment. But the sanction would be legal only. It would have no moral validity.
You are splitting hairs. You reject the authority of the papacy. On this point your postion and that of the Greeks is the same.
Really?
Vatican I dogmatized the universal jurisdiction of the Roman Pontiff. If you don't deny that verbally, you certainly deny it by your actions, because you don't submit to the universal jurisdiction of the man you admit is the validly elected Roman Pontiff.
Is the NO a valid Mass when celebrated according to the rubrics? (Let's go further: "when celebrated in Latin according to the rubrics" ... gets ICEL out of the picture. :-)) If you say, "Yes, but it's ugly and a poor expression of the faith," that's okay. If you say "No" or "Maybe," (and I know for a fact that at least some SSPX adherents say those things, because I've heard them say it) that's a heresy against the indefectibility of the Church.