I think the consensus is that Corbin's quality is better than Sargent's, but their customer service is absolutely, unquestionably, horrible. I got a Corbin for my F3 because the stock saddle was pretty uncomfortable. I also got one (found it on e-bay for 1/2 price) for the VFR because my wife likes having a backrest. The seat itself is not an improvement over the stock seat, which was pretty comfortable. One thing I do not like about this Corbin is the square edges, which makes it difficult to go from edge to edge smoothly. Just my $.02.
It turned out the kangaroo was right.