Coefficient of Friction
Not sure which Amsoil you were using, but it could be that the Mobile 1 has more friction modifiers. This tends to lower the dynamic coefficient of friction of the fluid and thus a softer shift. However, Amsoil ATF has friction modifiers............quite a bit, I believe to be able to be used with the new chrysler vehicles. Although, Amsoil makes a GREAT fluid without the friction modifiers called Super Shift. It is like a synthetic version of Type F. If you were using this and switched to the Mobile 1, I could see there being a noticable difference. Mobile 1 is good, but why switch from Amsoil if you liked how it performed??
TG