I went with the Flexx bars because I knew they worked well from prior experience. It isn't the sweep or rise of the bars that make them work so well, its the "flex" that makes them better than other brands I've tried. The ends of the bars actually flex up and down when riding fast over rough terrain. But what is really happening is that the ATV itself is pitching back and forth over the rough terrain, and the rider and his hands on the handlebars can stay in the same place, with the ATV moving underneath them. It makes a big difference. Actually it makes more of a difference on a sport quad with a solid rear axle, because they can really pitch back and forth on a rough cross country course. The fully independent suspension of a sport ute already takes some of the pitching back and forth out of the equation, but the flex bars help eliminate the rest.
In years worth of desert racing I learned that some mods make more of a difference than others when it comes to endurance races. Adding 3 to 5 HP with an aftermarket exhaust may not improve your finishing position at all in a 100 mile race. Dialing in the suspension and handling can make a big difference though. I went from finishing 5th or 6th place in local desert races to a 2nd place finish at an AMA National desert race when I upgraded to Ohlins shocks on a DS 650. Suspension and handling win cross country races, not power. And improving rider comfort, while decreasing rider fatigue also make big differences in racing, and also for just aggressive trail riding (play racing with your buddies). I had a YFZ 450 that I put a Precision steering stabilizer on, and that allowed for a huge increase in speed over rough terrain. The Grizzly doesn't need a steering stabilizer as much because the EPS does that function for the most part. But other sport ute ATVs would certainly be helped by a steering stabilizer. I also put an slightly longer, and position adjustable thumb throttle on the YFZ 450, and that made a big difference. One other thing I did was install a slightly longer clutch actuating arm, which made the clutch pull feathery light. I had put a full FMF exhaust on the YFZ as well, but I really think the little things like Fasst Flexx bars, the steering stabilizer, the throttle lever, and the clutch actuating arm improved the capabilities of the quad more than the exhaust did, because they improved the capabilities of the rider.
Anyway, sorry for the side track. Just pointing out that mods like handlebars, controls, levers, etc. can make a big difference.