As with any FI setup you are shortening the life of your engine, how much shorter NO ONE CAN TELL YOU and anyone who does is simply being dishonest or delusional.
There are things you can change on the engine and beef up to help limit that accelerated aging, but that adds $$ to the equation. All in all your looking at spending almost as much on the SC and other upgrades as you are on buying the car, unless you just SC it. Whether that makes sense on a 5-6 yr old car with 100k on it is up to you. But remember, other things will go on your ///M and they are costly to fix. Got to pay to play
Btw, she is an amazing car STOCK, so if the SC doesn't make sense, don't let that stop you from getting one
Good luck and you can look for more information in the "Engine and Exhaust" section.