A lot has already been published on this French IR.
It is fully ICAO compliant so will be valid outside France, so French airspace (Class A base FL200, in general) is not relevant.
I think Whopity is right, and I think the French introduced this for one or both of the following reasons
1. In collusion (at the time, anyway
) with EASA, so as to create a fait accompli situation for the acceptance of the FCL008 IR proposal ("look, the French have already got it and it obviously works").
2. In the knowledge that the FCL008 IR is doomed (but no modern country actually wants to shaft its N-reg community)
I say this because the French IR is significantly more training-bulky than the proposed FCL008 IR (now called the CBM IR).