Since no one else jumped in here Ill answer based on my experience
Ive had a Fast back for 2 years, riders area is the same , passenger is different than the Sport and Square back. Cant compare to a Ultra Seat but compared to my RGC its about 1" lower and 1.5 back. They are great seats IMO very comfortable.
Ive been to C & C a few times they are not far from my work. I ve owned 3 of their seats and been happy with them all. I also tried a Squareback on the bike IMO not enough of a difference over the fastback to make a passenger happy. If you are riding 2up any more than around town you need to go Sport Tour. (the riders/drivers area is the same for all 3 seats)
2011 FLTRX, 103 Power Pak, Stage 1 with Power Vision and V & H Power Duals, SE A/C, Cee Bailey TRSSC 15", Progressive 940 rear,Mono Tubes Front, C & C Fastback Seat and some extras in black here and there
2005 Annv FLSTFI, Stage II 95 kit, lowered 2" - SOLD
2004 Road King Custom - SOLD
2004 Sportster 1200 r, Stage 1 - SOLD