I have some sympathy with Frog_ATC (and my Aunt is French too, she claims to come from the "oily" part of europe
)......
I have seen some very poor decision making being done in the skies over France and the sourthern UK, though I don't think you can claim it is only IMCr holders. I have known "partial pass" JAA IR wannabes (JAA FI's would you believe) fly IFR into France on a VFR flight plan. I have seen VFR pilots take off into OC010 at L2K and I have seen JAA IR holders too scared to file IFR so they cross the channel at 400'
I have also known FAA IR holders shoot approaches into French airports in a G reg. I don't consider this last one a dangerous flouting of the law though....more of a flouting of adminsitration seeing as if you are a non EU resident the DGAC will give you a JAA IR based upon the FAA IR anyway......(N or G it is the same). Of course I'd never do this or condone it. I believe all these bad decisions could be avoided with an achievable instrument qualification valid Eurowide.
My ideal would be an "enhanced" IMC valid in Europe with slightly stricter restrictions applied, but with greater privileges. By that I mean you need an IFR clearance to enter some sort of "controlled airspace" with it and more controlled airspace available to IMCr holders (e.g. Charlie / Delta airways to FL100)....
The problem with the JAA IR is that unless you have £10,000 to spare and 3-6 months of study, and perfect hearing, it is not achievable. My wife would rather we had a new car than I had a JAA IR......It'd be much better to have an IMCr euro-wide which can then lead on to a full JAA IR with credit being given for experience later on and hence a modular IR achievable by those that need it......