I have had my Onix for about 2 months now. As RogDog characterizes it, stiff but not harsh. I have Kyrsium Elite wheels which are known to be a bit on the harsh side, and it is nothing like my CADD5. I am 55 yrs old and needed a bike that could maximize my strength but also could be comfortable for a Century and Double. I wouldn't let the word stiff scare you. When I refer to stiff, I'm identifying very little flex in the bb and frame and transfer of power to the pedals. The ride is not "stiff nor harsh". It is not as soft as the Roubaix and others like it, but then again, energy doesn't get lost in the bb and frame either. If you want a little "softer" ride with this bike, then let 4 or 5 lbs pressure out of the tires. As it has been noted in other forums on this website, that would give you more of a softer ride than buying a softer carbon framed bike. You then have the option to put the 4 or 5 lbs pressure back in if you need it. If I am going on a road that is rough and has recently been chip sealed, I have always done this, regardless of the frame. And I really don't notice the lower air pressure except for a little softer ride. I also put the specialized bar phat on and wrapped it with gel tape (it doesn't need it, but I like things very soft where I put my hands). The bars are super comfortable and absorbs extra road vibration.
There are some things that I like very much about this bike. The wing bars are great, gives your hands a comfortable resting spot when climbing, the stiff FSA BB with the external bearings are nothing short of incredible. There is great transfer of energy from the pedals to the wheels. The price was right. It has a great look with the mix of nude carbon and paint and the finish is excellent. The seat wasn't anything to write home to Mom about, but then I had plans to use my existing Koobi anyway Prior to purchasing the bike, I talked to the guys at Orbea USA. They answered all my questions and I found them to be helpful, much more than mere marketers. I have not regrets with this bike.
BTW, I wish I could write in French the way you write in English.