Just got a tm4 in december, little difference between the two i believe pro 35 is more water resistant and comes with renovator trays, works out same cost as a tm+trays.
Great for bringing up the pile, its agitates pre sprays much quicker and more thorough then a duo, and great on looped pile.
Even with soft brushes it can pull up alot of fluff from some carpets but makes them look and feel great.
A worthy upgrade to consider imo, black brushes essential also