Jim,
I installed the black one in the Shearwater, but sold that boat after only a few outings because the footroom was too cramped for me. I then built a similar but slightly larger Merganser 17W and installed the Grande seat, which CLC now sells. After the first all-day paddle, though, I ripped it out and carved a full-butt seat out of 3" foam. After a full season of long trips, I am delighted with this seat and will never go back to a commercial seat. You can see photos and details on my Merganser page.
-Wes

I might add that the seat that comes with CLC kits, as cheap and odd as it looks, is as comfortable as any of the expensive commercial seats. I use the one that came with my Shearwater on my wooden desk chair. All of these seats, though, cushion only the pressure points. The carved seats are no thicker at those points, but cradle your entire bottom, which spreads the pressure over a large area, resulting in all-day comfort. They also give you much better control of performance boats like the Shearwater. -Wes

Jim,

I agree.  the best bet is to build your own seat.  I started out my Shearwater 17 H with the kit supplied seat.  My leg would go to sleep in 15 - 20 minutes.  I carved my own out of foam and that problem went away.  The added thigh support makes a big difference.  One word of warning:  Cut the low point of the seat down to no more than 1" thick with the rest cut to fit you.  After paddling the CLC demo boat right after mine, I found that I was sitting a touch high which greatly deminished stability.  I cut the seat some more and was able to loer my butt by about 1".  That made a significant difference.

Happy paddling

Paul