Running it on our 09 Ultra. Interesting comparison as we have a Corbin on our 06 CVO Ultra.
The Corbin is comfortable, we had it custom built at Corbin to fit our butts. It is quite firm but we do 500 miles days with no complaints. It fits both of us perfectly. We do have the HD Sheepskin on it to keep it cooler in the summer. The Corbin is heated
The Mustang is out of the box. I am 6'4" and it moves me forward & I wish it didn't. I am not uncomfortable & have done 400 miles a day on it. I use an 06 CVO Style backrest with it. If it placed me in the stock position I would say it is as comfortable as the Corbin & slightly softer. For Trudy, she loves it, she says it is slightly more comfortable for her as she doesn't weigh anything. The Mustang is not heated, they don't offer it.
She sits slightly lower on the Mustang than the Corbin.
Here are the only two shots I have of the Mustang on the bike, if you want to see something different let me know & I will take a couple shots.