I've just come back from an hour ride, doing some interval training on my new Specialized Roubaix. I'm delighted. Not only with the bike, which performs as well as I expected, but also with the utterly different and much more comfortable riding position yesterday's custom bike fitting session has achieved.
Take a look at the height of the saddle on my older Trek compared to the handlebars. (I've tried to straighten the pictures).
I'd pushed the saddle as far forward as it would go to compensate for the greater lean forward. This affected my leg position, so I'd raised the saddle (too high) to compensate. No wonder my back suffered after a long.
The custom fitted position on the new bike has the saddle at the correct height and a higher, shorter stem, with a smaller curve on the bars. The perspective on the two photos isn't quite the same, and on this one, the saddle is not higher than the bars. But they're closer than I'd expect.