I doubt that DSC is the problem. If you stay in DTC mode, the ESP is still on and allows you some drifting.
Un less you have a lease, put the money that you didn't spend on the DHP / Sport line on lowering the car and getting 18" wheels. Larger sway bars may be a good idea, but I would do the other mods 1st.
xdrive takes a toll on handling and specially steering feel, nothing new.