I've moved on to a Specialized Tarmac SL4 (team bike) but have decided to keep the Felt F1 as a backup/rain bike. I just could't bring myself to selling the F1. Did 4 hours on the Felt today while the SL4 is in for the fork recall. I really love both frames - the primary difference being the stiffness and straight line speed if the SK4 vs the tight but more compliant and comfortable feel of the F1.
@commfire - the FSA BB30 carbon cranks have worked flawlessly. Nice snug fit, zero creaking and plenty stiff.
Wow, this is one of the only testimonies I've seen that describes what we've measured. The slightly "slacker" more upright SL4 is slightly stiffer but a much lower STW. While having predictable "hands-off" handling, it is a bigger chore navigating tight descents and unpredictable sprints.
The nature of the Tarmac's handling is what Felt tried to mirror in their Z series.
You are lucky to be able to have both options in your stable!