Rich - you will be shocked to hear that I voted yes
I voted a straight yes without the extra conditions because I believe that on the whole this forum is very good at self moderation and you don't need the extra workload; and, if a vendor is truly interested in servicing the Classic Rover community they are probably already on here and would have the right to reply - or not.
As to Deborah's comments above - this is not directed at you, but you have raised "general" concerns that have previously been voiced, so my two cents follows.
First, the whole legal exposure thing... it's really not as simple as person A says something mean about person B and the forum is instantly found liable to the tune of a billionty quid. Have forums been sued and lost for some defamatory content? The answer is yes; however, those cases are a million miles removed from what we are talking about here. I am happy to swap a pm or two with you Rich if you want some legal perspective.
Second, I find the idea a trifle amusing that a few trolls have spent decades waiting in the wings for their opportunity to jump on the Classic Rover Forum to spew malicious and defamatory garbage about a supplier/vendor/fellow members/Mars Bars/etc.
The forum is pretty well self policed, so I for one don't really anticipate any major problems. I expect people to share their honest (if slightly subjective) experiences with fellow members, who will then make up their own minds. If lots of people have similar experiences with a seller, well... if it walks like a duck, and quacks like a duck...
Third, like several of our members I am overseas. This adds a premium to whatever I buy - in some cases shipping is an additional 30% of costs. I would truly love to know ahead of time if the re-manufactured widget I am spending my hard earned readies on is actually worth it. I would also love to know ahead of time if the person I am buying from has a reputation for being slow/unreliable/honest/dishonest, whatever. I can then prepare myself accordingly.
Ebay, Yelp, Amazon, to name just a few major websites - all of them allow feedback, both good and bad.
I do think that perhaps couching the question in terms of "should we allow
negative reviews" could be off putting to some. I see this as expanding our policy to allow balanced reviews - both good and bad.
TL/DR - yes