I think the “Ring ship” could fit into Star Trek pre-ENT somewhere. I’ve always found it an interesting design and was disappointed to learn that Christopher chalked its appearance up to a “mistake” in Ex Machina. It seemed a little closed-minded to me.
Don't misunderstand -- I'm quite fond of the ringship. But it's problematical to work it into canon as a ship named
Enterprise, or to explain retroactively why it would be included in the refit E's rec deck over NX-01. After all, it wasn't seen on Archer's wall display of past
Enterprises or on the TNG wall display of past
Enterprises (though of course NX-01 wasn't on the latter either). It is canonical that the design did exist pre-ENT, because a painting of it was seen on a tavern wall in "First Flight" and in Starfleet HQ in "Home." But we never saw any such ships in use onscreen, so it seemed reasonable to conclude that it was an unused prototype -- at least, unused by Starfleet as a ship named
Enterprise. Closed-minded? No, because I would've loved to include the ringship more fully. I didn't make the choice because of personal preference, but because it seemed the most logical interpretation of the evidence of canon.
Would I make the same choice today? Maybe not. Maybe I could work out a more creative hypothesis that incorporated the ringship more fully into Trek history. But what I offered in ExM was the best reconciliation I could devise at the time. After all, I wasn't telling the story of the ringship. I was telling the story of the TMP
Enterprise, and reconciling the continuity glitch raised by the ringship was a minor issue calling for a brief explanation, not a dissertation on the history of human starflight.