On the surface, the Felt seems a better deal. The F55 has Dura Ace and a wishbone carbon seat stay. The Scott S1 has Ultegra and no carbon seat stay.

Test ride them both. If the Scott feels better, then that's the one for you, even if it doesn't have the top-of-the-line Dura Ace. Comfortable Ultegra beats uncomfortable Dura Ace any day. OTOH, if the Felt feels better, then you get a comfortable ride and D/A :-)