since it is going to be you on either bike... neither is going to be faster, not really...
I have a domane as my endurance bike and a propel as my speed/aero bike...
I have a 5 mile section that I time myself on...I am maybe a 1/2mile an hour faster on the propel...the propel feels faster, but the clock does not lie...if I am riding a couple hours or less, the propel is a fun ride... if I am looking at longer rides, the domane is the ride hands down...
I would suggest you actually ride them both and go with the one you like the feel of the best when you are on it. Keep in mind, feeling fast is not necessarily really being faster, and keep in mind that if you are going to be doing long rides, you will wind up faster over the long haul on a bike you stay comfortable on, plus you will feel better at the end of the day.