thanks for the comments, and yes i watched the guy do the swap, i am quite capable of doing the job myself, just getting lazier as i get older, but i kept a close eye on the guy doing the job.

interestingly he didnt hook up a back-up battery and all i lost was my clock time and OBC data

radio stations stayed.

other interesting thing is, and it may well be imagination, but the car seems to be running ever so slightly better, im starting to think that the occasional battery disconnect and subsequent memory reset may be good for the car.