Which would yield more lateral grip: JCW sport suspension, or H sport springs on MCS struts? Regardless, of the decision.I will have both front and rear H sport sway bars. Thanks-

 

Now there is a common misconception. A sport suspension doesn't increase a car's grip to the road, just reduces oscillation, and helps flatten the car through corners. If you want more grip, you need wider wheels, and tires with a sticky compound.

That said, I do like the ride of a tuned suspension, however harsh it can be on rough roads.

Given the choice of suspensions, I'd go for the JCW because if a MINI dealer installs it, it's under warrenty. But, you still will need stickier tires, and definitely get rid of the run flats!