It really depends on your use I guess. The Roubaix is a great ride, extremely comfortable once fit to you personally.
the CruX...I can't say I've ridden one but I can say it is a apples-vs-oranges bike choice.
the CruX is for off road cross riding/racing, not really designed to be a "more comfortable Roubaix". The gearing is even off for real road riding (check out the front gearing for example).
If you want a comftable road bike, stick with the Roubaix. It will be a faster, better ride on pavement that the CruX. If you want more off road, go with the CruX (or better yet, an off road bike rather than a cross bike).
your post seems to me you want a road bike (unless I'm reading you incorrectly)...I'd stick with the Roubaix, it's one hell of a nice bike. I rode one all last season and loved it.