Hi
I had a stage 1 remap on my other daily car and it made a huge difference in performance , economy and driveabilty was much improved, thats a diesel as well.
but would recommend if you have it done , have it done properly, I paid £235 for mine and it took about 3 hours and was setup and checked on a dyno/rolling road they have.
some companies just flash a map in it and its not always setup correct to suit each individual car
cheers
Joe