Arguments for no, don't copy SE:
- One needs knowledge of the topic to upvote a certain post, too, even if he or she is just thanking.
- Copying SE causes a default skew towards higher-voted answers and questions, which is not an accurate description of the post.
- It's asymmetrical. Who doesn't like symmetry?
(I strongly agree with this opinion, so consider this answer with 1 more vote. Feel free to suggest more reasons in the comments, or simply edit the post if you can.)
Feel free to criticise.