I see no concrete reason why there should be badges made for posting milestone or merits received.
There is enough motive to seek to gain merits, and I don't see why we should enocurage people to post to get badges
Reporter badges would be to encourage members to use the 'report' button and also to reward those who already use it
Reporter statistics are not public, unlike post count and merits which can be viewed in the profile and determines the members rank and ability to wear, avatars and signatures.
Enough motive? You mean the means of ranking up? Sure but we are talking about "earned" merit. Not the merit people started with because they had already been here. Besides ranking up above Legendary then there isn't too much of a merit unless you mean just having a visual merit display. But its been proven time and time again that images work better. Its why a lot of advertisements use elaborate images to gain the attention. A nice design of a badge for 500 and 1000 merit "earned" would be a good thing in my opinion.