The open nature of a hypothetical public wiki makes it highly unlikely that cutting edge information will make it in there from those who are in the know.
What we want would be a highly detailed repository of well-written, well-indexed information. That is also what the kidiots and television producers are looking for.
If it is as visible or accessible as any other site, then all we can expect from contributors is what is on every other site. Although the days of devastating bans (i.e., sassy) are over for now, certain things do not need public attention.
The mere addition of certain workups might send too much public attention down paths which are currently wide open. Anyone is welcome to take that journey, but we don't need carnival barkers drawing attention to those roads less traveled.
Wikipedia is very well trafficked. They have a ton of editors, bots, and channels dedicated solely towards watching recent edits for vandalism or errors. If an idiot decides to alter the start date for the War of 1812 to the year 1813, no harm done. If an idiot decides to engage in subtle vandalism of a chemical workup, expect somebody to follow it and wind up gassed, hit with shrapnel, or staring down an hot acid volcano. Chemistry doesn't allow much room for error, no matter how good the intentions.
We have the option of cloning Wikipedia's appearance, layout, navigation, and editing interface without having to clone their broad acceptance of edits from the whole world. The MediaWiki technology is great, but Wikipedia's openness will fail at something as authoritative, dangerous, and illegal as clandestine chemistry.
If the crowd isn't right, this could turn into a mere reformatting of what is already public in the Rhodium archives, when in fact the goal should be to dig deep in journals, patent databases, and the Hive, to pull up good information and lay it out in a more integrated and useful manner than the current textfilez collection on the Rhodium mirrors. Organizational software like MediaWiki has made that method of website presentation obsolete and clunky.
The scope and mission statement have to be very focused going in. If it's open to the public, and focuses on drugs in general (a la Erowid), then you'll get a bunch of that drug crowd coming through for the bioactivity side of things, which will lower the SnR on the chemistry side of things. There are already plenty of places to talk about drugs and drug use, so there is no advantage in having yet another, especially if it comes at the expense of cogent chemistry discussion.
Wikis aren't as easily cleaned as forums. In a forum, a pointless post can be deleted, after which it will never bother the forum again. Pointless threads can be locked or shipped off to a trash forum. Repetitive queries can be directed to TFSE then mercilessly mocked. On a wiki, cruft just seems to spread, especially on the talk pages.
Wiki talk pages are terrible when multiple people are trying to have multiple conversations on the same subject, all of which are interconnected, and logically belonging in a linear manner.
I think the goal needs to be the leveraging of the best of both worlds. If the Wiki were a companion to a forum, on which is placed only quality, vetted information, by quality, vetted members, with all the discussion remaining in the threads. The forum model is working fine for what it is supposed to do, and The Vespiary is working fine as far as forums go.
What we're really looking for is a new way to present the reference of first resort, which for now, happens to be Rhodium.
I think a critical point here is that Wikipedia itself would never work on a forum equivalent, or anything close. Wikipedia needed everything Wikified for the collaboration to function. Forums work fine for collaboration in the chemical underground. The big advantage for starting a CC Wiki is in how information is presented and in what format, not the collaboration behind the pages being presented.