ifitaintBoeing - thank you - that document is one I'd not tracked down, and clarifies things massively.
blagger - quite. One hopes that the proof of the pudding is in the CRI skill test; for myself I'm willing to be tested and if I'm not up to it, retrain or give up - and then take advice from much more experienced instructors wherever it's available. What the general success/pass/fail rate, particularly from 300hr PPLs (about the point in my flying career where I made my greatest every f**k up in the air) however, I have no idea.
Billiebob - Interesting, since I gather that the FI(R)/FI ratings contain a "no aerobatics" restriction don't they? [I'm not an FI, and would not consider myself competent to teach aerobatics even if I was - I just about maintain enough currency to fly basic manoeuvres and get myself out of trouble, so am purely interested.]
G