Hi,
I've fitted a set of smootharides from Minisport to my MPI Clubman Estate. The Up-side: being adjustable you can set the ride height almost anywhere that you want - I wanted a more height than the standard (and rather poor quality) MPI cones had. Secondly, the ride quality is vastly improved - I also retained the Koni Mpi dampers. They are fairly easy to fit - you will need a compressor for the fronts.
One down-side: I had one of the rear extension pieces fail on the way back from the IMM in Bavaria. I have now made 2 new rear extension pieces from 25mm Stainless whch will prevent any further problems. I am in discussions with Minisport over this. As an Aeronautical engineer by trade I do not think that the minisport extensions are up to the job - this can be easily overcome by a jobbing workshop making another pair for you.
I would definitely NOT go back to the old set-up - I would use the Minisport smootharides every time, especially if they re-design the extension pieces. Hope this helps you decide (pm me if you need any further info.)
I put a bit on my web site about the smootharides at
http://www.stallard-.....0Estate 3.htm