In theory it shouldn't but different states apply different standards, I know of people having to sit extras simply to convert what they have in other EASA countries to a UK one, as said the UK seem to operate to a higher standard.. The old licences were recognised as one of the best, therefore in the worlds eyes a lot of UK EASA licenced Engineers are those that have simply converted over....another advantage is as a lot of the world speaks English, having a CAA one infers by the fact you passed it, you can read, write and talk the language, a French one as an example wouldn't.