Your reasoning parallels mine. I too have a 2012 and bought the Akrapovic full stainless steel exhaust. They make two full systems (2) which are identical, one S.S. and one Titanium. S.S. for street is fine.
The system is a work of art, shame to have to cover most of it with the lower. Benefits:
1 Much better sound, but not loud unless you remove the baffle (one bolt);
2 Much freer breathing without OEM system;
3 Much better looking without OEM system, and;
4 Weight loss and less perceived frame rail heat (at least in my case)
I also installed a PVC with Dynojet's map for this system, but might could have done without it.
Hard Racing, a vendor who supports this forum, sells them and the price is much less than the identical system with the BMW logo thereon. You can order directly from them if you wish.
Now you only have to decide whether to get the Titanium or CF cannister. I got the Titanium which I think looks great with my Motorsports color.