Jan the rules apply to the registration where ever the aircraft is in the world. If its on the N reg but in Blighty and flown by an FAA certified pilot then the aircraft must be operated according to the FARs. In addition the pilot (and aircraft) may be governed by the rules of the country in which the aircraft is operated.
It does raise an interesting question I hadn't previously considered; a CAA pilot is entitled to fly an N reg aircraft in UK airspace - presumably said pilot is not required to comply with the FARs since he does not hold a FAA ticket? I wonder?
As to the question why would you worry about the MSA? If you are crossing in VMC and the weather is suitable you are not restricted by the MSA. Indeed in the right conditions you can literally see your whole way across and make a reasonably informed judgement as to whether (or not) the flight is possible. If on the other hand you are crossing with the expectation of entering IMC then you would be nuts not to carry oxygen and have the capability not only to use it but to use it for potentially a longer period of time. I accept then if the winds are strong you may well wish to be above the MSA if not much higher, but then again that may be another variation of conditions to avoid for a first time crossing.
Last edited by Fuji Abound; 27th August 2012 at 19:28.