well my personal opinion on this, i may be right or wrong, is that most of these moves are "conditional" lag tactics, meaning they are lag tactics if abused, but they have a purpose if used in the right situation(eg SBH A+B tip range to knock characters like ivy out of SSE or mitsu out of SR to prevent having to deal with them and to discourage use.(hope i got that terminology right)) or like using 1AA to stop taki posession sidestep very quickly.
i do believe however, that not only is 2[A+B] SBH A+B a lag tactic, but also a very shoddy mixup, especially to online players who recognize it, as it is punishable, and easy to block. what gets it true lag tactic status in my opinion, is that if 2[A+B] SBH puts siggy close to his opponent, he can either SBH K when they go to block SBH A+B or he can still SBH A+B. although this can get annoying sometimes, any player who has a fairly moderate amount of ability(i use that loosely, i guess anybody could if they happened to figure it out, even as a N008) will at very least block it, and perhaps even punish accordingly. the biggest thing tho is that we make sure not to use any one of these moves excessively, and we will be ok.
BTW, i believe 3 SCH K isn't a lag tactic, but is fairly lag boosted. the best way to interupt it, is to try to train yourself to recognize the exact time or close to when 3 SCH hits your block, and as soon as that happens, input the move you want to use to interrupt 3 SCH K
(eg. siggy1 vs siggy2(yea, i only use siggy, so its all i know XP): siggy 1 3 SCH, siggy2 uses 6K immediately on 6 block to interrupt 6 SCH K)i'll admit, ur timing needs to be more precise online, but its just like offline when it comes to punishing.
but 4 sig, this is all kind of iffy, cause these things dont work as well offline, but they do work offline none the less, u know?
P.S. i still think 2A+B/2[A+B] is a total lag tactic anyways, unless someone can tell me otherwise.