Custom cab VS Comercial cab

I Am currently looking into bids for a new engine for our department. I am interested on some input on Comercial VS Custom cabs. Our department is settled on freightliner chasies. I would like to see us go to the custom cab as I feel it offers better maneuverability for our rural drives without the giant engine compartment out front. Another issue is our maintenece on these comercial trucks seams to be never ending. I need some good arguments for our board, so any input will help.