You certainly can run a GAL Sync to the personal (Default) contact folder and it will not affect their personal contacts, but simple add to them

if they manually copied them there already, there would be duplicates after the sync.

If using Enterprise edition and Relationship Group Manager, many people create a separate distribution list

which will be set to the default folder, then attach the new template to the new distribution list.  Be sure not to put the same people in both.

That way if your devices don't support it, you can add them to that list.

Does this help?