I'm confused. Why can't you wait two months for the 52cm Triban and spend the £200 on, say, some swanky wheels or a bunch of nice kit to go with the Triban? And has been said, don't believe the press release, only way to confirm sizing is try before you buy. It's a lot of money to waste getting the wrong size bike simply because you didn't check it out in advance. Trust me, I speak from experience!
I think we can safely say that of all the "so many different opinions", the one that seems pretty consistent is - don't get the Nashville. Up to you if you want to listen or not. Beats me why you posted if all you're seeking is validation of a choice you've already made.
Stu