Is there any actual benefit to merits? Do higher merited users get more features?
No man, no extra benefits, the only benefit is that it allows you to rank up. The side effect is that you build kind of reputation of non-shitposter as the spam is a big issue nowadays.
You can quick look here >
https://bitcointalk.org/index.php?topic=2534500.msg25841174#post_guide_meritCheck Extra info links too.