I haven't been left stranded by EFI yet, but I've had 3 different vehicles with recurring electronics issues that were EFI components. Took a lot of effort to figure out exactly where the problem was coming from in one case, the others were found by researching the trouble code online and seeing how the lots of other people having the same problem fixed it.
Did you catch that little part- the only reason it was easy to fix is because the problems with EFI that I was having were common, not rare.
As far as my personal bikes, I haven't had any issues with my EFI Versys, but have had some issues starting a VSTROM with a dead battery because of the EFI (the battery wasn't dead because of EFI - starting was hard when it would've been easier without EFI). It will push start, but you have to do it more than once to get the fuel pressure up enough to get the engine running. If it will fire just a little, it will cough and start running. Don't know if I could've done it by myself on flat ground.
As far as riding buddies, most of them haven't had issues, but I know several people who have:
-In-tank fuel pump came loose during ride. Trailside disassembly and fixed good enough to limp it back to truck (Husaberg).
-Sensor wire frayed and bike died on a dirt road trip couple of hundred miles from the trucks. Was lucky enough to find a dealer on the phone who could tell us what the code meant, and we traced the wire from that component. (KTM)
-In-tank fuel pump failed on the trail, requiring bike to be hauled/pushed back to the truck. (I think Husaberg again, but not sure)
I think we are still a couple of generations away from EFI on dirt bikes being "robust" enough for me personally. Probably there with the street bikes already.
There are a lot of people who say that carbs may be easier to fix, but EFI you don't have to fix very often. #1 - that hasn't been my experience. I have only ever had one carb problem on a bike, and it was just a dirty carb.
My personal observation is that a carb failure will likely happen when the bike is in the garage, while an EFI failure will likely happen when the bike is on the trail/road. I keep more/better tools in the garage, so that's where I'd like to do my work.