entity_export - where can it be used? I want to make use of the entity_export function for data migration. I see on the doc page http://drupalcontrib.org/api/drupal/contributions!entity!entity.module/function/entity_export/7 that

Note: Currently, this only works for entity types provided with the entity CRUD API.

How would I know if a module fits this criteria? Is it simply if it has the entity module as a dependency?
If the module has been properly written en utilises the full Entity CRUD API there should not be a problem. In most modules this should be the case.

However the Entity module does more (like exposing entities to Views). If the dependency was only used for such a specific case, it might be possible that the module comes with un-exportable entities.

If you want to narrow this down you could search the module for HOOK_entity_info() (change hook to module name) and see what controller class is used. If it is EntityAPIController it is likely to utilise the CRUD API.