Disclaimer: I might be wrong!
My logic would be that it is unlikely, on the std chip, that any of the alternative settings would result in more advanced ignition / leaner mixture. the only worry would be if any of the pins could provide an unwanted voltage on a link - which would be a pretty bad design unless the same port is used for diagnostics.
Mo has a cat fitted; so the Lambda sensor should help keep the fueling somewhere about right - so really he needs an ignition setting to prevent pinking on low octane fuel (no knock detectors).
First idea is not to change anything unless the engine pinks on the low grade stuff.
If pinking does occur, try one of the low octane settings for the BB chip, its unlikely to be any worse!
the best bet is to try and get alternative code plugs from a BM dealer - I've read elsewhere on this board that they only cost about £2.
I've read on AdvRider that some guys regularly use 89RON without problems - but US RONs are different to UK/EU RONs.
Another alternative is to lose the CAT and carry a bottle of TetraBoost (real lead additive) to dose up any low grade fuel.
I could, I suppose, swap the std chip back into my 1100 and try it but I don't have any crap fuel to put in the tank!
HTH
Mark