I just think that you should enjoy the car as standard for a while and then remap it later so that it feels like an appreciable step up.
Also, I'm not convinced about the potential reliability of a 320cdi with a remap.
The OM642 V6 isn't always the most reliable engine and a remap might exacerbate this.
If you have it remapped early on and it breaks something, you would need to pay a lot of money to get it working again.
If you remap it after you've had it for a while and it breaks, just sell it and get something new.