This thread seems to have become about open source vs. closed source, and what exactly counts as industry standard or best of breed.
I think there is a much more sensible policy we could pursue here:
1. If there is a reasonably well-developed open source alternative, use it. 2. If not, use whatever the best priced solution is. 3. Use the community to help decide what the best solution is.
Given Wikipedia's inherent systemic bias towards young geeky men with computing experience, I'm sure some reasonably pragmatic advisers can be sought on a voluntary basis from within Wikimedia UK's membership.
Can I suggest to the board and to WMUK staffers to consider this very reasonable (I hope) proposal: find 3-5 computer folk from the community to give feedback on technical choices using the above guidelines. I'd be happy to help on that. But do it quietly and informally in the background, so every debate like this doesn't become some kind of ideological slanging match on the merits or otherwise of open source.
Often, if one isn't committed dogmatically to free software at any cost, there are good compromises one can make. For instance, there are increasingly good non-open-source alternatives to Photoshop available (on the Mac, there's Pixelmator, for instance) that cost significantly less.
Even if you are a free software fundamentalist, consider: less money spent on closed source software produces less evil overall, and leaves more money over to spend on the charitable aims of the Wikimedia movement.
Having some technical oversight from the community in the form of a lightweight 'geek cabal'* seems like it might be quite important given other discussions about things like mailing lists, having to run a locally-hosted OTRS-type system for fundraising email, and funding of tool development (stuff like Wikidata, Commons upload tools for projects like GLAM).
I think the point is to find a straightforward, drama-minimising way of making technical decisions in a pragmatic way but that's still informed by our values and preference for openness.
* The first rule of the cabal: you do not talk about how there is no cabal. Obviously.