I'm no expert on this but I will add one thing to your benefit list. Some of the aftermarket belts haven't been holding up so well. I think re-using the OEM belt will be more reliable.
As for the steering weight, I have yet to hear of anyone who would not like it heavier. I do like the M3 steering as it is but a little more weight wouldn't hurt.
Welcome to the forum. You have an E92 M3? If so, post pics.