Nice bike.
5 pounds = 6 watts on an 8% climb but no benefit on flat
Frame aerodynamics (who really knows) but let's say 5 watts @ 20 mph. This assumes that the rider set up of the Felt is the same as the Trek. If you are lower on the Felt then there could be a significant aero advantage.
Wheels = 3 to 5 watts @ 20 mph and could be more
New Drive Train (gears and chain) = 6 watts New drive train 2% old drive train 5%, power produced =200 watts. 10-4=6 watts.
Frame and wheel flex = 5 watts **
Total Power Advantage Flat Terrain = 21 watts
Total Power Advantage Climbing = 17 watts
Assuming the rider is producing 200 watts (typical for 20 mph) then the new bike would provide approximately 10% savings in power to go the same speed as the old bike.
** This is a highly debated matter. Some believe that the flex in wheels and the frame is captured when it rebounds. In a mechanical system that is true. The problem is that this system is part mechanical and part human. The human has to put in a counter force capture the flex in the frame and wheels as they spring back. Sprinters know this without using any science. They are slower with flexible frames. Also, on a stiff frame and wheels, it feels good or easier to put in more power. It is hard to explain. I think that the frame flex causes riders to "fight" the flex as the body has to recapture the power as the frame springs back plus put in more. I am just trying to explain what I feel and IMO others feel when they ride a bike with a stiffer frame and better wheels that are engineered as a system.