The "Ergo" seat has a softer top layer, like a pillow top on a mattress! The foam underneath is a bit firmer.
I guess the "Ergo" seat is a bit more comfortable than the plank that came with my 890 Duke R, but not a lot. It's fairly cheap money, so it may be worth a try for you as opposed to the more expensive Corbin option. I'll ride it for a while longer, but I suspect that I may try the Seat Concepts foam/cover combo.