I have finaly bought an XF after looking for about 5 months. It is a 3.0D S PL (pre facelift). Having tested a number of cars I was convinced the ride on the 20s is degraded too much and asked them to swap the wheels to 19s, which they duly did. I believe the compromise between ride and handling is well judged, I know it is still firm, but it seems very well damped. The 19s for me are as big as the wheels should go though.