Hopz,
There are many failure modes for that silver colored fpc. You're right that most, maybe even all, are moisture related. But remember that without a bypass cable or the ability to make a bypass cable from the old fpc, or a spare fpc, you're stuck if it dies. Insurance with some spare wire so you can cut off the old connector and rig power is only pennies for some wire, a bypass cable is a little over $20, and a spare fpc is $150- any one of those 3 can get you going. Remember that there have been at least a couple THOUSAND of these failures, not just a few, based on published data from the UK GS website, extrapolated to all countries/models/sales numbers. Based on that, I think some insurance while traveling is only prudent.
Here is a summary of failure issues
The fpc carries 7A that it takes to run the pump- that means it gets warm. When it cools there are possibilities of condensation or sucking water into it. It sits in a well that doesn't drain and collects water from riding in the rain or just washing the bike, The uncoated fpc housing can corrode easily and when it does, it will break the seal that protects the circuit board from water intrusion. Sometimes failure is immediate or you might get a few miles or a couple starts worth of warning. In any case, the sealer used is a cheap production method and not up to the task - it will leak even on the new replacement parts that are coated to prevent corrosion. The gasket around the fpc does a bad job at keeping water out of the lower part of the well- only 2 clamping screws into plastic, another bad design bit. In summary, the well is a stupid design, the part is badly made, and the replacement only addresses some failure modes (not all). It is not clear whether the board itself has issues from poor heat management in the design (the reason the housing is finned) and I have not yet dissected a new fpc to see if there have been circuit board changes. Failures of the new part are reported, also but I think its too early for meaningful comparisons about rate which in any case will be complicated by the fact that most folks put the replacement in with silicon sealer or a good grease coating on the gasket. something missing from the original factory assembly method.
Maybe if you live in AZ and never wash your bike, you can forget about the possibility of the fpc failing but considering how easy (even cheap) it is to be prepared, I wouldn't choose to be one of those folks who ignores this issue- unless perhaps I never went more than a few miles from home. Remember that dealers and parts places are typically not available if you get a weekend failure on the road.
This bit reminds me a lot of the ballast resistors on old Chrysler built stuff from the 70s that only cost $1.25 at the time and failed regularly, preventing the starter from running. But in that case, there was typically a car parts place somewhere nearby that had one. Still, some owners (including me) threw a spare in the glovebox when they went any distance. Eventually I got the chance to use my spare- think I was way up in the Canadian woods fishing at the time.