The FCR can be made to work well,it just takes a little fiddling.On one trip I got 92km out of mine with about 2l left in the tank(9.5l tank)On mine,I put a lineweaver jet kit in it,which eliminated the accel pump-or was supposed to.It worked well and increased the mileage tremendously .95% of the time,it was perfect but when you needed to give it a hard crack,it would bog.I ended up putting the pump rod back in but then at low speeds through the rough stuff when you were sort of blipping the throttle,it would load up.I ended up taking the carb off,filling the bowl and activating the throttle.The gas that shot out hit the wall past my workbench about 6ft away-and kept doing it for about 3 seconds.It took just a little throttle to do this so you can see why it was loading up.Interestingly,there was a round boss on the carb body behind the pump cam(almost like it was made for this) so I drilled and tapped it and put in a spring loaded screw and adjusted it to limit the cam travel so I had about a .5-.75 sec pump squirt(as low as I could get it before it wouldn't activate at all)This was the cure in the end.
As for fuel injection,I like it.I've been an auto mechanic for the last 20+ years and well remember standing in a snow bank adjusting choke thermostat tension,choke pull,fast idle etc while the fan blew -20' air over you-brrrr.I don't miss that at all.Mapping issues aside,I think the biggest issue with the bike systems are their simplicity.Most are an open loop system and those that aren't don't have much more than a cts and o2 sensor.It's hard to get an FI system to operate in all situations with such limited inputs.I've never seen it mentioned but what bothers me more about the bike systems is the lack of fuel capacity.Whether just due to the space the pump takes up or tank design or both I don't know but 6.5 l is a pretty skimpy capacity imo.It would be ok for MX but scrambles or off road it would be a curse.