I like your idea, this is something which can be further worked on.
Merit Sources are just as 'centralized' as the 'Default Trust'. Plus if you take into consideration things like bias, time spent by merit sources on the forum etc. It isn't the best way to distribute merit or the efficient one, to say the least.
What I had in mind was a sort of stake system... So Let's say 20,000 merits monthly would be distributed to people who 'contribute' to the forum. Each 'upvote' will get you X amount of stakes, Depending on the rank of the member who upvoted your post. To prevent spam, You could exclude upvotes from newbies, jr.member and members. The "sMerit" will function the same way as it does now.
You would get 1 stake if a Full member upvotes your post.
You would get 2 stakes if a Sr Member upvotes your post.
You would get 3 stakes if a Hero Member Upvotes your post.
You would get 4 stakes if a Legendary user upvotes your post.
You would get 5 stakes if a mod upvotes your post.
You would get 10 stakes if an Admin upvotes your post.
This sort of system will consolidate for things like bias from merit sources and time which is required to 'lookout' for merit-worthy posts. Let's be honest here, Many boards are 'under-merited' because of the reasons I mentioned.
Been wondering why I was stuck at newbie rank for a while even thought I tried making decent contribution and after doing a search, I just stumbled on this thread.
Like your idea, it would give decent chance for more people.