Marcion and Itacism

Now that I am focusing on this problem of the eta in the name of the Christian god, I am remembering a conversation I had with David Trobisch a while back. It is common knowledge that the Marcionites referenced their god as χρηστός rather than χριστός. Even Strong has this in their entry for the Greek word - "appears as a spelling variant for the unfamiliar Christus (Xristos). (In Greek the two words were pronounced alike.)" (F. F. Bruce, The Books of Acts, 368).

I noted to Trobisch that an old book on Christian inscriptions noted that there were far more references in the inscriptions to χρηστός rather than χριστός. In fact even χρειστός appeared more often than χριστός. The point here is that many people have noted that itacism must have been present in Christianity from a very early period. An example from Marcionitism:

1 Corinth. ix. 8 Marcion reads εὶ οὐχὶ καὶ ὁ νόμος ταῦτα λέγει, whereas Epiphanius reads ἢ οὐχὶ καὶ ὁ νόμος ταῦτα λέγει. Here there appears to have been no falsification. Probably ἢ and εὶ were interchanged by itacism. [Samuel Davidson, A Treatise on Biblical Criticism: Exhibiting a Systematic View, Volume 2 p. 49]