Have a look at the Pro Limit Race seat! Have had one for 3 seasons and it's the best seatharness I've had. Unlike previous harnesses I had this one has a very stiff shape. It gives excellent back support. The hook is a bit on the low side but gives the harness a very direct feel of what's happening with your rig. Also the spreaderbar release system on the Pro Limits is pretty much bombproof. I've seen Dakine's, Ion's and Mystics been torn apart on the release system. Pro Limits don't tear or release, the hook just bends. Simply buy a new hook instead of buying a new harness
Also had a Rambler and always rated that as a good one. However it did wear quickly and lost it's shape after 2 seasons. But the new Ramblers do have that covered. They have the same quality as the Race I have.
So if your more a freeride/freerace surfer get a Rambler. But if your looking for a seatharness that will give you that slalom/speed feeling get a Race!