Is it inconsistancy on the part pf the writers... or is there something special about Henry that Henry can leave and return to Storybrook (the pilot episode) but when the Jersey boy left Storybrook he could not return?
Yes, Henry is descended from an Enchanted Forest bloodline. Owen wasn't.
I do wonder how Henry got to Storybrook. The first season it is indicated that Gold arranged Henry's adoption. How did Henry get there if no one could see the town?
The same way Emma did: by being of an Enchanted Forest bloodline, and thus able to see Storybrooke even when it was cursed.
Presumably, Neal/Baelfire could have come there during the curse, as well.