I have been riding road bikes since the late 1980's, and have ridden every material except titanium (although with any luck, will be ordering a Firefly Ti bike). I built up the Fenix SL frame/fork with full Dura Ace 9000, Thomson X2 stem and Masterpiece post, HED Belgium C2 rims (24 front / 28 rear) with Chris King R45 hubs and Vittoria Rubino Pro day-to-day tires (and latex tubes), 3T ergonova aluminum bars, Specialized Toupe Pro seat and Garmin Vector 2 pedals. It is definitely not the lightest bike I've ever owned, but it is by FAR the most comfortable. It is stiff, but forgiving - although the rim and tire/tube combo help with this as well.
I've put a few hundred miles on the bike and the only downside (to me) is that the bike doesn't have the quickest handling in the world. I personally like bikes that are "twitchy"....and this isn't one of them. To somewhat put it in context, it's like comparing a BMW M5 (Ridley) to a Porsche Cayman GT4 (purpose-built "high speed" racing bike) - the M5 will outclass and outcomfort the GT4, especially for the long haul, but the GT4 will outhandle it any day of the week.
Now, that's not to say that the Fenix SL doesn't handle well and is incapable; I'm just comparing it to a full-on crit machine that you can effortlessly dive into corners with. You can do that with the Ridley as well, it just takes a little more forethought. Your mileage may vary. On a recent mountain descent on some rather poor roads, I found myself on the brakes much more than I would be with previous bikes I've ridden/owned.
But the comfort - oh man. This is a bike that you want to keep riding. It's stiff where it needs to be, and yet surprisingly compliant.....but doesn't feel totally "dead" like some other carbon bikes I've owned.
A word about the Dura Ace 9000 mechanical groupset - holy crap. I rode Shimano in the 1990's through to the mid 2000's, and used Ultegra back then - a very capable groupset that shifted flawlessly. I then went to SRAM back in 2007 for my race, bike since it was light and cheap.....if I killed it, it would be much cheaper to replace. I've been using SRAM right up until this spring, but grew tired of the crummy feel of the shifting. Between the brakes, crankset and the effortless mechanical shifting (including the front derailleur), Shimano knocked it out of the park with the D/A 9000 groupset. I will never go back to SRAM.
Oh, I almost forgot - the Fenix SL frame/fork appear to be made in China. I was rather disappointed by this as I was under the impression that Ridley made all of their stuff in Belgium, but this doesn't seem to be the case. Either way, the frame and fork appear to be well constructed and with good tolerances.