Seems fairly rare - searched and found little on people getting their ECU's remapped professionally... The benefits they claim sound really impressive (211BHP - 231BHP and 320nm - 340nm torque and increase in MPG) for the price of £275 inc dyno runs to measure the increase.

Other sources suggest if your car is non-turbo the gains are not really that noticable...

Anyone have any info they can share or had this done?