I know of few guys with Spannish JAR licences who have had problems with the Spannisg CAA when it comes to adding ratings etc to their licences that were completed outside of Spain. In one guys case it took them two months to add an A320 rating. They required photocopies of all the instructors licences, the Sims certificate and pretty much everything else that was not nailed down. They also told another guy that he should have asked permision from them to complete the type rating outside of the Spannish JAA. Spain seems to be one of these countries that has not taken the full concept of JAA on
I guess thats why some companies want to avoid Spannish Licences, theyre more hastle than its worth. Of course you can always convert it to a UK Licence when you hve finished!