the examiner for the skills test has the power (and I've seen this happen) to abandon the flight test before starting it if s/he feels the candidates knowledge of airspace/systems etc is not up to scratch during pre-test questioning
That's right, the examiner can fail you on the oral exam alone.
The only other thing that is perhaps worth mentioning is that my instrument rating instructor reckoned that the FAA did have a slight problem with maintaining high standards for the IR and that he knew people who in his opinion shouldn't have been granted their IRs. This is perhaps inevitable to some extent considering that while the CAA employs staff examiners to conduct initial IRs the FAA doesn't (it does for CFI though).
I don't buy that - if one is talking about relevant flying competence. If one is talking about flying NDB holds to 0.1 degree accuracy
then certainly the JAA system is going to be more rigorous, but if one was going to match competence to the actual requirements of IFR flight, there is no difference between the two.
In truth neither system prepares you fully for European
private IFR flight - there are loads of operational details which are not taught. The FAA system gets away with it because it does teach you what you need to know for flying IFR in the USA. The JAA system gets away with it because the vast majority of the output ends up in the airlines, in the RHS with a captain in the LHS and the captain keeps an eye on things.
The majority of instructors teaching the JAA stuff are highly prejudiced against the FAA regime and everything connected with it. The vast majority of them have zero knowledge of any FAA training, and the vast majority of JAA instructors have never flown private IFR to anywhere significant. The FAA IR flight training is bl00dy hard work and 10 times harder than anything that's needed for real.
And a few months after the IR checkride it's all irrelevant because there are 3 things that matter in IFR flight
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