Hope you enjoy the boat.
As for the seat, having a moveable seet is kinda moot in the CFS because it's such a tub (as you mentioned) that trim is rarely ever an issue, even with the biggest paddlers (me at 220). I have friends with CFSs that plop down NRS foam seats on top to give them more lift, but this almost always effects how the backband sits. I never found it necessary, either, though I know it can be helpful for rolls, etc...I guess I'm the rare breed that likes being low in the boat.
I also have a friend with the Jackson Happy Seat system in his CFS and he swears by it. Usually I would just crank the bulkhead back as far as possible and cram myself in there...never had a problem with anything. The new backband in there, while not top of the line, is pretty dern good compared to the original Bomber Gear one that I broke. Even without drilling for the elastic lifters it stayed pretty well on my back all the time.
The one thing I wish it had was a ratcheting backband system. My procedure was always get in and pull myself as far forward in the boat with one hand on the combing and with the other reach around and pull the cam strap tight on the backband. Not too much of a pain in the ass, but when you're putting in micro eddies in deep gorges with sheer cliffs of crumbly to hold onto, it can be trying, to say the least, attempting to stay out of the current. There might be away, with enough creativity, to bolt on a ratchet system for a solid IR Reggie backband or other.