I do not use synthetics either during break-in. I switch after the motors has some miles on them first. I may be all wrong about it but... I am comfortable with doing this way so this is how I will continue to do it and that is the bottom line. You have to feel comfortable with what you do with your car.
Viper's come from the factory with Mobil 1, are they pre-broken in with petro oil then switched or has Mopar found that it doesn't matter?
Chuck