Several years ago a fishforum started a thread and, because they got bad service there, began to bash the lfs. Several other unhappy members joined. The owner eventually sued the group and won. The decision was published ( I can't remember the site link).
Indeed, information placed online can be used as evidence and, as such, I do not think a product review, per se is a good idea. HOWEVER, I think a product SPECS thread is fine, listing eg a particular pump, what this gph is, what size tank it is good for, etc, is OK and could be pinned.
What I think would be optimal, is to get these manufacturers in as sponsor companies under Williams new sponsor section and use this to ask forum to ask question, troubleshoot, etc. SH