That said, it would be really cool if, in the full release, they had a special 'thank you' item for early access players. This would be a nice gesture, but certainly not necessary.
While it is a nice thought, I don't like any exclusives that affect gameplay. It's like you're not supposed to have that. Feels like cheating. Rather just throw it away than use it. And on the other hand there will be some people wanting to have that exclusive item but can't.
Something that doesn't affect gameplay would be fine. Like exclusive hair, perhaps.
