I'm back and no near-death experiences.
I can confirm the car definately feels different after the ECU re-set. Firstly, I was being pushed back further in the seat than normal and secondly, pulling away "spiritedly" from some lights, I span the rears and did a nice "Dukes of Hazzard" squiggle down the road. First time that's happened since purchase.
Did about 20 miles so I guess the fun will end soon. I suppose you could reset every day when setting off but can't be bothered. Will wait for visit to Abbey.