If you are gonna upgrade your seat, I would suggest you bypass the Corbin and other off the rack units and just get a real custom seat. My suggestion (from prior experience on other bikes) would be Rick Mayer. You send him the seat pan and he makes you a true custom seat. For the rider section only being custom, passenger as stock and covered in vynil, it's $330 US. The seat he makes is just plain better than Corbin. The advantage to Corbin is that you don't have to give up your seat pan while its being made. But the Corbin is still a one size fits most (sort of kinda we hope). The Mayer is made for you, where you sit on the bike, your weight, hip width, etc. He has a form to fill out and requires 2 photos of you on the bike. His Brother Bill Mayer makes a very very similar seat (they are the same) and Russell makes the Day long saddle which was developed by Rick and Bill's dad. The Russell actually uses a spring in it like a car seat. All 3 are the best you can get for real comfort. Rick is the cheapest though.
Rick Mayer
Bill Mayer
Russell Day Long