So there are two issues here.
1) How to correctly log flight time.
2) Rules for transatlantic crossing.
Number two is fairly easy to deal with, as VFR flights are not allowed over FL65 or FL95 in the NAT system (here I assume that realworld aircrafts fly above these levels) so they must fly under IFR.
Which brings us to number one.
If your authority states, for example per 14CFR 61.51 (c) that you must log instrument time during the time you are operating solely by reference to instruments in actual or simulated instrument conditions, then do so. What you are efectively logging is IMC time. Those are the rules under FAA.
Under JAA you log IFR whenever you are flying under instrument flight RULES. Even if you are flying in VMC the JAA regards flight time on an IFR plan as instrument flight time. Whether you, me or anybody else on the operating end agree with this practice is irrelevant, those are the rules.
When I finished my business in the US, I had nearly 2000hrs TT and roughly 120 IMC - in the IFR column. I keep a separate logbook for my FAA flying, this basically means that I have in excess of 1200 hrs IFR but only around 150 hrs IMC. Arguing if this is correct/ padding/ unreal world conditions, though interesting and timeconsuming, is purely academic as I doubt none of us will see a change in the rules.
As long as everybody plays by the same rules... where they may play.