All I want to express quickly at the moment is my concern regarding associating the number of postings (as a condition from being established) with TRs.
Established members with a necessary numbers of reviews could be a good idea.
But take into account people registered here for a certain length of time (more then a year or two) which also have the necessary numbers of reviews. They are as trusty as the rest. If anybody has some PM queries on their reviews, who is to say those people don't answer PMs even if they don't post???