Pros and Cons of adding Dinan S3 to 4.6is

[SeattleYates]

I was considering adding a Dinan S3 (the full signature kit with supercharger) to my 2003 4.6is, which only has 36K miles on it. Any comments on the pros/cons of this mod? Here are a few potential issues I've identified (please tell me how important they are, and add others!):

Pros
- 450 hp and big boost in torque, especially at low-end
- nicer (throatier) sound
- Doesn't dramatically alter exterior appearance of the vehicle
- Even with this add-on, I'd be way ahead financially vs. buying a new X5 and modifying it to comparable performance level

Cons
- Cost (15K+ Ouch!)
- Wear and tear - is the suspension/transmission, etc. of the stock 4.6is up to handling that additional power?
- Doesn't dramatically alter exterior appearance of the vehicle
- Resale - rumor is that people don't like to buy used X5's with Dinan kits because they assume the car has been driven aggressively by prior owner