Whether fingers burnt or not - if committing forces "in support" of an EU "Greater Good" there might be a touch less guilt for the poli's.
I suppose my bottom line is that the CVFs will be good for Britain whether in the EU or out of it (in a Norwegian kind of way).
The only reason to say that they are not needed is if you can always guarantee a substantial US presence.
Well, with the New Europia there might be no political desire to share the stage with Uncle Sam. Also - we haven't (as UK / NATO / EU) supported every American adventure with boots, boats and flying machines...
so why assume that they will back ours?