Yes, I have only recently realized just how interesting they are. If the Roubaix is robust enough to handle the rough, cobbled roads of northern France, then it ough to be robust enough to tour. As we've seen, the Roubaix has quite low gearing, it's ligh and nimble enough to climb and descend well with a small amount of baggage. The stack and reach geometry is almost the same as my touring bike, so long distance comfort is assured. The frame has clearance for 28mm tyres. So lots of pluses, and I can follow your thinking with the RS.

Despite having two touring bikes in my garage already, this ultralight touring paradigm has grown on me since I met such a tourist in New Zealand a few years ago. He was riding a CF road bike with seat post rack fitted and was carrying little more than a set of street clothes and a rain jacket. And could cover up to 200km per day quite comfortably if so desired. Since I'm considering a new road bike, I think the Roubaix might just be the one that could do double duty as a both roadie and a tourer.