Can't speak for Ultimate Seats, but the RZ is AWESOME. I know from my previous bike (VTX) lots of VTX riders loved the Ultimate seats on those. But with the RZ, if you start feeling a "hot spot". all you have to do is add or release air, and it's a whole new seat. Hot spot gone.
I had an Ultimate seat on my 09 FLHT. Very well made and a lot of people swear by them. I have never ridden a bike with the RZ so I can't compare. But the Ultimate is an excellent conventional (no air bladder) seat.
Had an Ultimate Seat on a V-Star 950 I had before my EG Classic. All I can say is it wasn't for me. The Mustang Super Touring seat on my HD works 100% better and cost a good chunk less. Had looked at the RZ before choosing the Mustang but with a 29 1/2" inseam an inflatable seat would not have been a good thing.
I have an Ultimate seat on my Yamaha Roadliner and it's the best seat ive owned on a bike Just bought an 40 Ultra and it came with a Mustang which did not work for me. Bought a used HD comfort seam seat and rode it yesterday for 4 hours. What a beating. I am ordering a Ultimate set up Monday for the Ultra. Cant cut corners on comfort. Ultimate spoiled me. Did 2100 miles on the Rodaliner two summers ago and did great the whole trip.