Im really surprised you dont want the roush axle back, I fitted the roush to our S500, as an axle back, its quite when in the driveway, has a nice deep rumble under acceleration, does not drone when cruising, and has zero raspiness, very happy with it, I didnt fit it for performance, only to give it a little bit extra sound, I like the belnd of quiet at idle and deeper note under acceleration, its great for what I wanted.
I agree with others comments, exhuast note is a personal choice, what one likes others dislike, so get what feels right for you, try attending a club event, where you can talk to owners and listen to the cars first hand, it will help in your decision.