It depends on the model? Which one was it and how old? Freightliner makes many versions of the M2 chassis that it sounds like you are describing. I had the model with the ISC 350/1000 Cat. I even towed a 8,000lb. trailer around the hilly NE. The fan kick in you described happened very seldom.
Frightliner makes an M2 like the Senecas use that is the ISB Cat with less HP and torque. Some had no air brakes and maybe a cheaper insulation package to save $.
A unit with the engine in front will never be as quiet as one with the engine in the rear. I would rather have something that handles better and don't mind engine sound vs. wind noise and squeaks and rattles. We always laugh when passing the white knuckle cheap A's while I have 1 finger on the wheel cruising.
You really need to test drive the units you are considering in the environment where you will use them.