Which frameset....

If I'm not mistaken, the P3 SL is aluminum and the QR is carbon. Make your choice based on which material you like more.

Assuming both frames fit you well, the aerodynamic difference between these two is probably negligible. Frame design has a relatively small effect on aerodynamics in general.

Any difference in weight will also be negligible. You can see for yourself at analyticcycling.com.

If I were making this purchase, I would probably choose the Cervelo, because I like them as a company and because I don't have the money to replace carbon if I crash. I ride an aluminum Dual right now, and the ride can sometimes be harsh, but I don't have to worry about crashes.

i agree with the above mentioned poster about using a non-carbon frameset as your first bike. But you will eventually enjoy the upgrade to a carbon and softer ride