Here is the scenario...regional FO with no upgrade in sight. Goal is delta. Do I leave the regional to get some valuable airbus time at spirit or virgin or do I stay put? I am concerned delta will see I have only been at the LCC for a short time (say a year or so) and may have lots of questions about why I'm leaving the carrier after such a short time. (Or worse won't want to interview me at all) How important is company loyalty? Thoughts?