This sounds rather scary, not something I would expect on an IFR flight plan. While one can always argue with ATC, they have powerful means of retaliation (detours, holdings). Without the (foreign) pilot realizing, he suddenly loses separation and needs to take care of airspace. When planning IFR, I don't familiarize myself with airspaces at all. Never understood why one would want to have airspace G high up, as soon as there's radar coverage, it should be at least E in my opinion.
Regarding France -- I've never experienced any requirements to be > FL100 or > FL120 on an IFR flight. Just the other day I flew all the way from Paris / Toussus to Stuttgart at FL090. In France, I prefer IFR even on CAVOK days so I don't have to deal with their amazing airspace maze during weekdays.
Last edited by achimha; 15th Aug 2012 at 07:24.