More droop is going to keep the front tyres on the ground longer. The unwanted side effect is that more droop is going to generate a lot more cornering traction which (on carpet at least) means traction roll with the narrow Minis. I've always found that the best balance in carpet is minimum droop above zero (0.5mm-1mm shock shaft extension). On tarmac it probably matters less, but more droop will make the car feel slow to respond. I would always build the shocks for the right amount of droop and run the car low, rather than run the car high to limit the droop - a low car is a fast car.