you'll loose the sharpness of the ACE if you move to AT's as your on road grip levels will change slightly as will the flex in the sidewall. That said, I put 'General Grabber AT2s' on my TD5 and the've proved to be a very good choice.
Slightly higher on road noise, better traction off road and wearing very well. 5 of them for the price of 4 BFG's