I'm really torn when it comes to this. I like the idea of moderator approval, but there are a few issues with that. The act of checking a box isn't a big deal, but I could see there being a lot of accusations of favoritism (or perhaps more than just accusations...?). There are a lot of people who help on a regular basis but likely wouldn't fit the criteria because their knowledge is either borderline or they simply don't have the best attitude. Such a person would likely get upset. I could also see us getting tons of requests to become an Accepted Helper, much like we do for current "positions of power".
Of course, as I stated, basing it on postcount is problematic as well. We've banned several members who had over 1000 posts and 100 thanks. Some people are able to just barely glide by for a while.
It seems to me that there isn't a really good way of doing this. Whatever method is used, there will be drawbacks. The only thing I can think of (aside from scrapping the idea altogether) is to set it up as a ranking system. That way, someone would have to work their way up to Accepted Helper, Trusted Helper, Sponsored Helper, or whatever (the highest rank would need approval). But then, do we really need two ranking systems?
I'm basically on the fence here and just throwing out thoughts/ideas.