Auto Express has an online write-up of the MCSa with JCW upgrade (which takes the car from 168 to only 203, instead of the 210 of the manual), and they are not very flattering!
… the MINI’s conventional six-speed auto not only drains power, but is slow to change gear, too … the lethargic box masks the beefy engine’s considerable verve … response never feels sharp … Sport mode doesn’t help matters … Steptronic paddles that are small and awkwardly positioned … the auto box seems to take away a vital feeling of connection …
I guess I drive a different MINI to them!
I will agree that the auto box takes away part of the driving – I don’t have to bother changing gears. But other than that, I have just as much fun in my ’05 MCSa as I did in my JCW equipped ’03. And the keenness of the transmission to shift down when I ask for more power happily masks any transmission loss.
In the end, the MINI is great fun to drive no matter which transmission you have. If you enjoy shifting gears and pressing the clutch regularly, the manual is excellent. But if, like me, you feel like being lazy but still having fun, the MCSa is very satisfying – and if MINI USA ever allows the JCW upgrade, you can have even more power and wheel spin!
M&I / GBMINI 
I didn’t realize it had “shipped”. Ian, are you going to install the JCW kit on yours?
They sure are funny. My car is modded with everything a JCW kit includes except a cylinder head and it pulls like all hell through the gears. Shifting is fantastic.
Chris,
The JCW upgrade for MCSa “shipped” last year – but not for USA! Auto Express is a UK magazine
I only know from the drive from the Boston airport to MINI of Peabody with Ian. It seemed to accelerate quite nice.