The work of each [viz., Theodotus, Asclepiades, Hermophilus, and Apolloniades] was current in many copies, so that copies were easily obtained and compared. It is unlikely that the ready availability of copies was due to purely private, individual copying. Despite its scholastic aspect, this textual work in Rome was not disinterested but stood in the service of exegesis and theological argument, which makes it still more probable that the emended texts were produced in numerous copies, the better to promote their wide use and thus sustain a particular theological viewpoint.1
I can't help but remember Bart Ehrman's work, particularly in The Orthodox Corruption of Scripture: The Effect of Early Christological Controversies on the Text of the New Testament (London and New York: Oxford University Press, 1993). Ehrman's thesis is that the "corruption" (in its technical, text-critical sense of variation rather than its popular sense of degradation) of scripture wasn't the sole domain of heterodox scribes and theologians; orthodox (or proto-orthodox) tinkerers also affected the readings in the text. As I read Ehrman, however, I couldn't help but think that Ehrman's analyses depended on too little data. That is, Ehrman made his claim for the orthodox corruption of scripture on the basis of individual variant readings and only rarely considered (i) the effect of a given change on the subsequent manuscript tradition or (ii) the effect of a given theological perspective on potentially problematic readings throughout a given manuscript. Of these, the latter is even rarer than the former.
Gamble's discussion, however, makes clear what Ehrman assumes: that changes to individual manuscripts had limited effect upon the tradition as a whole. If a person or a group of people wanted to conscientiously alter the reading of a text and wanted that change to displace an earlier reading, additional steps had to be taken. In the case of the Little Labyrinth that Eusebius cites, the heterodox teachers in Rome were involved not just in corrupting scriptural texts but also in disseminating their corrupted texts. The Little Labyrinth mocks its opponents' folly: "[The readings] of Asclepiades, for example, do not agree with those of Theodotus. And many of these can be obtained, because their disciples have assiduously written the corrections, as they call them, that is the corruptions, of each of them" (Eus. H.E. 5.28.17; my emphasis). But behind the author's scorn for the numerous copies then in circulation and the ammunition these copies provide against the scribes responsible for them, we can sense a certain frustration—even concern—that the flood of corrupted manuscripts might actually affect the Church's reception of the sacred tradition.
Perhaps, given the paucity and selectivity of the data that survives from antiquity, such evidence against the "proto-orthodox corruptors" of scripture is unlikely to have survived. Even so, this is the type of data I would look for in support of Ehrman's thesis. Gamble, who takes up the question directly of the relation between the authority invested in a text, its textual stability, and its preservation, provides a more helpful basis for historical discussion in that he appeals to actual textual evidence. Ehrman, it seems to me, often relies on the hermeneutical potential and theological possibilities of particular variants and their placement within the very interpretive framework for which he's arguing (viz., the orthodox corruption of scripture).
1 Harry Y. Gamble, Books and Readers in the Early Church: A History of Early Christian Texts (New Haven and London: Yale University Press, 1995), 123.