I'm a VERY happy Ultimate seat owner. I never put a lot of seat time into a Mustang but I'm very happy with the Ultimate. My bike is a little different ('02 VS-1100) but I can sit in mine all day long and my butt is just fine afterwards. A very different reaction to the stock seat. Note, I did get the backrest which is part of why I really like it.
2002 V-Star 1100
You don't stop riding when you get old, you get old when you stop riding
2004 BMW K1200GT
1995 BMW 1100 LT
1970 Honda 500/4
1969 Kawasaki 500HD - 3 cylinder rocket
1968 Yamaha 250