It would be Ok as long as you fast-forward the opening credits.
I'm curious to know why you think ENT would hold better than the others? If I were to pick a series that I can imagine holding well on audio, ENT would hardly be the first to come to mind.
Generally, Trek series could hold on audio much better than the movies, which are far more action-oriented and visual. I'm guessing that TNG might hold well on audio since it was quite "talky". DS9 would hold very well except for the episodes that had a lot of action or space battle scenes; but there are quite a few episodes like "Duet" that are based on dialogue and character interaction, that I can imagine working very well on audio. You would lose the advantage of seeing the emotions on character's faces, but most of them acted very well with their voices, too.
The ideal ENT opening credits would be a silent movie -- visual with a mute button!
Just based on my own impressions of the shows, I've always thought ENT was both dialogue-heavy and visually uninteresting. I'm generalizing, of course, and no doubt there were exceptions somewhere in the four years.
Funny you mention DS9's "Duet", I was thinking the same thing, that it would be a fine audio drama. I contrast it with "Emissary", where all the Wormhole Prophets scenes were heavily dependent on visuals and couldn't be made to work as audio.