I can see the problems as time on useful types (the 61 is being phased out wherever possible) and licencing.
I have seen others with the FAA ATPL have trouble overseas due to a lack of type endorsements. The US does not use type endorsements for all helicopter types and this has caused troubles getting licences converted.
1350 twin doesn't meet most captaincy requirements and copilot expat positions are hard to come by. The Helijet option has been discussed.
You didn't mention multi-PIC, another hurdle.