another factor that I find unconvincing in Saengers argument - without having read his book, but as it is summarized in the article linked by OP - is his assertion that pretty much all of classical and late antiquity was scriptura continua-country.

Even if the claim were right, nothing in particular would follow from that. The idea that scriptio continua was an obstacle to reading is purely Saenger's own allegation. He claims there's empirical evidence for it, but the single study he cites to support that - this one - doesn't show anything of the kind. That study didn't even test the effects of scriptio continua vs. interpuncta: it tested the ability to vocalise text presented at various speeds and in windows of various sizes.

The majority of evidence for reading out loud in antiquity consists of passages with a potential aural metaphor. What I mean by that is expressions that describe text using aural/oral imagery: like when in English we say "That book says...", or when we write "As I said above..." and things like that. If you disregard that form of expression, what we're left with is oral reading attached specifically to social functions: teacher-student settings, performance, rhetorical readings, that kind of thing. Which is entirely unsurprising.

No one has actually disputed Gavrilov's refutation since it came out. Even Saenger gave up the idea (at least he hasn't written anything further on the subject).