Electone...
I believe the benefit of the FRONT setting is to match the sound of your surrounds and centre with the main speakers.
Beneficial if your watching HT and you get a left to right pan, or front to rear sound transition. As I understand it, the receiver sets the centre and surrounds to match your mains as close as possible. Nice not to hear a change in tone as a truck drives by in the background..
Flat - as it says.. All speakers are of similar quality..
Comes down to that one thats flipped around here quite alot - let your ears make the decision. Technically there isnt a right or wrong unless your speaker quality is miles apart.
Try a week set at each.... Or grab some material, sit down and check the detail of each for 1/2 an hour then make your decision.
A