Well please allow me to share my experience. A couple of years ago I got tired of the stock seat, and had MCC do the double decker on my seat. I bought a used slightly abused Ultimate driver's seat off ebay to use while my seat was being done. After getting my seat back from MCC, I used it for about a year. I then had the opportunity to buy a used Wide Touring Mustang set. The Mustang was the studded version without driver's backrest. I used it for about a year, and then traded with someone for the Sport Touring Mustang set with driver's backrest non-studded. I thought I wanted the backrest.
Well I decided I didn't like the backrest, and since a needed a little extra cash a couple of months ago, I sold it. I have since went back to my MCC seat.
Now with that background I will give you my assesment. The MCC seat is a decent upgrade from stock. By the way I had the double decker mod done. However, I can only go about 30 minutes before I start shifting in the seat trying to keep from getting serious butt burn. Since I am a seasoned long distance rider, with some shifting I can stay on the MCC seat for an hour.
Now I did not like the way the Ultimate fit me. It felt like I was sitting on top of the bike.
As for the Mustand Wide Touring, well let's just say that in the year that I used it I went on 3 different trip of over 1500 miles. I would sit in the saddle for as much as 2 hours at a time and only have the slightest discomfort. I was actually more comfortable after 2 hours in the Mustang then I am after 30 minutes in the MCC.
Now let me end this post by saying that this is all my experience and is not applicable to anyone else's possible experience. The guys at MCC were great to work with and are great members of this site. Also alot of it comes down to what type of riding you are going to be doing.