It shouldn't really matter. If you are appropriately certificated under the JAR regulations it doesn't really matter if your flying experience is from another part of the world since the flying is the same. Maybe you aren't up to date with JAR OPS if you have worked outside Europe but that should really not be a problem.
The only issue I see is that employers tend to prefer references from an employer that is in the region, not in the other part of the world. I guess that the same goes with all other occupations.