I have both the Corbin and the Sargent. I can say that the Sargent needs nothing else, it felt good from the start. I like the Corbin because of the way it looks and because I like leather, it just feels good. Unfortunately the seating position and shape make it uncomfortable in comparison to the Sargent. On smooth roads the Corbin doesn't bother me, but throw bumps in, and it beats the wrong parts leaving me in pain. There is too much rise in the front for the riding position putting too much pressure on the soft parts. Had they retained the original seating position, it wouldn't be bad, unfortunately they chose to make you sit farther back and a tad lower causing you to lean over more. Risers do not help this for me, risers were rather uncomfortable for me since it just felt as if my arms were higher and felt uncomfortable on long trips. (800+ mile days.)
I put the Sargent back on last week after a particularly uncomfortable weekend last week and felt more comfortable immediately. I am considering having it recovered in leather. I have also considered continuing breaking in the Corbin, but am not sure any more breaking in would help its issues. I have over 3000 miles on it and my experience is that soft parts don't break in a seat, that issue is best accomplished through proper seat position and shape.
The verdict is still out for me, I have not decided what to do but I will say that out of the box, the Sargent is a very comfortable seat.