My friend and fellow Mini enthusiast here in town has a D series in his P'up - it's more than enough power and extremely reliable - he's done 25K miles in his so far and loved almost every minute of it.
Hey Magneto, is your friends a stock motor? when you say "more than enough power" is it really more than enough? I'm not sure how quick mine will be especially with the built motor, but I really hoping for the "hold on to something" feeling when I hit the gas.
As john says, the power should be about the same as a stock B series but Ill have better/useable gearing, and it's bit lighter which should all add up to a more drivability and steerable daily monster.
I wish there was someone local in my area that I could take me for a ride, so anxious to see how she performs!