Just test rode both the Defy Advanced Pro 0 and Roubaix Expert over the weekend. These are upper-mid range builds with Ultegra Di2 and carbon wheels with DT Swiss internal hubs. I tried a M/L Defy and a 56 Roubaix. They handle similarly: more planted than a full race bike but still responsive and fun. I really liked both bikes. The Roubaix is very slightly longer. The Defy feels a bit stiffer on the front end and BB although that might be just my perception due to the Future Shock. They are both compliant, comfortable bikes. The Roubaix's Future Shock is noticeable on bigger hits, less so on chatter. The bikes seem to weigh about the same. The Defy's new handlebar and carry-over seatpost actually work very well. The Defy comes with tubeless 28s and can definitely fit up to 32s. The Roubaix comes with tubed 28s and can apparently fit 32s (according to the shop I went to).
The Defy is $5,575 retail, $225 less than the Roubaix. The Defy also comes with a nice Giant branded Bluetooth / ANT+ double-sided power meter. There is a $800 less expensive Roubaix without carbon wheels which the shop I went to did not have in stock. I think the Defy is overall a better deal given the build. I also think the Defy looks better, the holographic paint is cool in the sun. I don't like the look or the setup hassle of the Defy's bulky/bizarre Propel-esque "Stealth" stem. Really don't like the look of the Roubaix seatpost and bar either. The Future Shock seems a bit gimmicky to me, but people who own the bike seem to genuinely like it. The Roubaix is undeniably a great bike, you can't go wrong with either (and you shouldn't at these prices).
Last edited by Hiro11; 03-11-19 at 01:20 PM.