Just to be completely UNHELPFUL
Get an Isaac... get an Isaac
Or an EMC2...
Seriously... I have not had either a Scott or a Felt (though the Felt TT bikes look preety darn smoooove), and we don't own either in this family of bike-nuts...
However, the consensus in discussions in this house, and with our various training/racing partners is a preference for Scott...
Good luck... what a fabulous decision to have to make!
So much better than pasta or rice for tea...
You will post pix once you have chosen, yes?