Why is everyone concern about running fi in closed loop mode? You can tune and use fi in open loop. Many fi atv and dirt bikes don't use an o2 and Many of the sport bike aftermarket fi tuners eliminate the o2 and you just tune the engine on a dyno as would with a carb.

Because the air flow curve in a high performance two stroke will move 200 to 500 RPM depending upon the pipe temperature.  The fuel flow or map values being off 200 to 500 RPM makes for a lousy running engine.  This is one of the main problems that I and all of the engine manufactures have encountered trying to run a two stroke in open loop.

The video of the CR 500 indicates they are having the same problem mentioned above.  If you listen closely to the engine it is close to being in tune on one section of the track and way off on another section of the track.  This is because the pipe temperature is changing and the fuel demand is not the same on one section of the track compared to another section of the track at the same RPM and throttle position.  Did you notice that they had their lap top trying to make adjustments trying to hit this moving fuel flow target that they have not gained enough experience to realize that the fuel target is constantly moving. 

I was not impressed with their EFI efforts.  I have seen and worked on a lot of carburated CR 500s that ran better than their fuel injected bike. 

If you try to run a high performance two stroke in closed loop and know what shape air/fuel curve the engine needs we have just changed the name of the look up table from RPM vs throttle position to RPM vs air/fuel ratio.  My findings indicated that the fuel and spark map for a high performance two stroke needs to have at least a 5 dimensional sensing and mapping capability. 

Most EFI 4 strokes run great with  2 dimension mapping systems.  There is a lot more phenomena occurring during one engine revolution in a two stroke than a 4 stroke.