A most intriguing discussion occurs in Metzger's Textual Commentary in relation to the NA/UBS reading at Acts 9:25a. The preferred reading of those editions is LABONTES DE OI MAQHTAI AUTOU NUKTOS, supported by p74 Aleph A B C 81c pc vg-st,ww; whereas the Byzantine MSS (as well as E Psi 33vid 1739 gig vg-cl sy, and, with variation, 6 81*; with conflation 1175) read LABONTES DE AUTON OI MAQHTAI NUKTOS.
The difference involves more than just a change of word order, being reflected in various modern translations as either "his disciples took him by night" — indicating Paul's own disciples; or "the disciples took him by night" — indicating believers in general. The consistent pattern in the book of Acts (some 30+ occurrences) is to state "disciples" without a modifier, even when it is obvious that certain believers are a disciple of a given person (e.g. Ac 19:1, disciples of Apollos; 20:1, 7, Ephesian disciples of Paul, etc.). The only modified occurrence of the word appears in Ac 9:1, but even there it is inclusive, "the disciples of the Lord".
Metzger, Textual Commentary, admits that OI MAQHTAI AUTOU appears to be "the oldest reading extant in the manuscripts," and of course this explains the main text reading of NA/UBS. Yet Metzger immediately provides compelling reasons why the "oldest reading" -- as found among the Alexandrian witnesses -- cannot possibly be correct: "it is scarcely conceivable that Jewish converts to Christianity at Damascus would be called 'Paul's disciples'"; nor can "the genitive AUTOU" be "construed as the object of LABONTES"; nor can it be "gratuitously" assumed "that these disciples had been Paul's 'companions on the way to Damascus, who . . . had themselves come to the faith".
Yet Metzger (and, presumably, the entire NA/UBS Committee) seem unwilling to allow in this case that (for once, at the very least!) the Byzantine Textform has preserved the correct reading, AUTON. Instead, the reader of the Textual Commentary is treated to a tour de force that is reminiscent of Westcott and Hort's "Western non-interpolation" terminology:
"The most satisfactory solution appears to be the conjecture [!] that the oldest extant text arose through scribal inadvertence, when an original AUTON was taken as AUTOU" -- i. e., the Byzantine AUTON indeed is original, but not as it appears within the Byzantine Textform!
To push this conjectural envelope further, Metzger cites Haenchen on Acts, where in loc. Haenchen repeats and extends the fictional/conjectural hypothesis:
"MAQHTAI AUTOU must be an early corruption" (Haenchen, 332)
"Here AUTON has been misread as AUTOU . . . The reading AUTON in the later MSS is thus a correction [!] which — for once — is correct" (Haenchen, 332n3)!
Thus — even though all the evidence points to the Byzantine AUTON as the original reading in this location, those who reject the Byzantine text under almost all circumstances instead prefer to hypothesize a conjectural "original" reading that became totally "lost" through error permeating all earlier MSS, yet which "error" then was "corrected" by the mass of later Byzantine scribes.
Forgive me for asking, but why should Occam and his Razor not be applied in the present instance? Why engage in speculative gymnastics and textual legerdemain to defend as "conjecturally original" a reading that clearly exists among the vast mass of manuscripts? Certainly the simpler solution would be to admit "Alexandrian archetypal error" at this point.
I suppose the real difficulty is similar to the problem faced by Westcott and Hort when they could not bring themselves to acknowledge "Alexandrian non-original interpolations" at those points termed "Western non-interpolations." But even so -- if Metzger's opinion reflects that of the NA/UBS Committee, why then should they not have "conjectured" the "original [Byzantine] reading" as the main text rather than publish what appears to be held as incorrect on all counts (as cf. Ac 16:12)? More importantly, what then about all the various modern translations that continue to perpetuate this acknowledged error by reading "his disciples" in Acts 9:25? Food for thought.