I have owned Series 4 and 6 decks from Exmark and run the Velocity from Scag. Over a broad spectrum of properties, field grass to soaked fescue the Scag will win. If you mow perfectly dry weed free cool season grass weekly then the Exmark will win hands down. Riding Green I agree with you Deere has a winner in the Ziron as well.
Knowledge is knowing a tomato is a fruit, wisdom is not using it in a fruit salad.