If you are doing uphills and offroading, I would recommend a TC, but for a 9HP, you are going to have to go with the Comet 40 series TC. It is expensive though. The Comet 30 series is rated for 8HP and under. You could probably push it to 9HP, but you will go through belts a lot faster
What sort of off roading are you thinking of? Just a bit of grass, or will it be serious offroad