The open station tractors are harder to shift than the cab models, I guess the linkage differences. I seem to remember an improvement publication from Kubota about it (could be wrong)-might be worth calling the dealer to see what the bulletin entails. Just because there's a bulletin doesn't mean Kubota will pick up the tab on it, so be prepared for that.
The DT models were really hard to shift...I hated them. When I worked at a dealer, they sold I think one DT and said never again....all others from that point on were hydraulic shuttle models, and to my knowledge have had NO problems. And they shift a LOT easier.