I could not disagree any more about the Corbin seats. I've had several on different bikes over the years and found them to be very comfortable. They are firm but at the end of a long day my butt wants firm instead.
The only drawback I can see to a Corbin on the FJR is you lose the seat height adjustability.
Had Seth Laam build me a seat for the FJR. Did not like it at all. Had a Russell on a ST1300. Did not like it at all. The pocket they put you in does not work for me, BUT I am surely in the minority and may be banned forever for those views.
I will say the Laam seat is very fine craftsmanship and Seth was a pleasure to work with on the phone and he did hold to his ship date for me. Same with the RDL folks. If those seats work for you then the money is well spent.
Currently ride with a Sargent seat front and rear. Bought it for my 08 FJR and now have it on the 14.
Whatever you chose if you have the ride in option for your build I would highly recommend that.