My idea is that merit should have more of a purpose than merely being required for ranking up. Merit could also function as a post moderating system where posts that earn merit can be viewed first. So spam and useless comments fall to the bottom and the best comments rise to the top.
You could switch between the "merit" mode and "normal" mode if you wanted to see all comments in the order they were written.
Can't you do this already with the merit stats function?
If you go to your profile and click merit, and then on the "menu" click merit again (because on my case it shows my posts that were awarded merit, but I can "go back one level"), you can see the merit stats link.
I think this might work as a direct link for what I'm saying.
https://bitcointalk.org/index.php?action=merit;statsAfter this you can view top merit topics; top merit replies; top merit users, etc.
Isn't this what you wanted? I know it's not the same as being viewed first, but this way you can still filter posts by merit if you want, so it doesn't have to be a default for all users.