Corporate Express ( http://ce.com.au/
) used Twiki for the entire IT department, about 100 people and 10 webs.
In general the upgrade from Twiki to FOSWiki went fine. As part of the upgrade we moved from internal passwords and accounts to doing ActiveDirectory
integrated authentication, as the wiki was promoted from a dev to a production application.
There was some bitching that with the regular auth system, you could read the pages without logging in, whereas with AD integration we need to always log in even to see it, and it's not a transparent login. However, I'm fairly sure this is not your problem, and just a function of becoming a prod application. However, if the AD auth does NOT support unauthenticated readonly it might be useful to find a way to add it.
Since we aren't a heavy user in terms of complexity (we don't use a lot of plugins, it is mostly just as a plain wiki) all functionality seems to be retained and the changeover was pretty much effortless and unremarkable (which is a good good thing).
By far the most comments from users were regarding the new default look and feel (we had default Twiki and now use default FOSWiki). In general, the clearer and less cluttered look and feel was positively received.
However, in attempting to make a cleaner look, FOSWiki appears to have also made the wiki less useful in some ways.
In particular, for a "working" wiki there is WAY too much whitespace. Margins and borders throughout the new design a plentiful and thick, which has noticably reduced the amount of usable space on the screen, and caused many more things to wrap or switch to iframe scrolling than in the previous default look and feel.
There's a large margin around the page as a whole, then another large margin around the left menu, and another large margin around the content area. Once you are scrolled down past the menu, and you've used a subheading or two and bullets, we've found that the amount of usable space on the screen gets a low as half the actual screen width.
This is especially the case with the programming team using multiple wide screen monitors in 90 degree rotated portrait aspects, who typically have screen resolutions of something like 1050(width)x1680(height).
I'd expect this same issue to impact some of our regular business users with cheap commodity business PCs with 1024x768 screens. The new style is more difficult to use on anything less than 1200ish width, and since the programming and admin teams in particular have lots of literal code and shell blocks, they report a noticeable increase in the number of these blocks that have to be sideways scrolled now (which is really annoying).
We have two main suggestions.
1. Keep the current look and feel, but please pay more attention to efficient use of screen real estate (especially horozontal real-estate). You could easy trim back your margins to half what they are now with little ill effect.
Finally, once other thing I've noticed with the new design is the horrible Jump/Search look and feel.
These are two rather small textboxes, using a really ugly and hard to read font. Using them is harder than it should be, and there's tons of blank space around them going unused.
I'd prefer to see a larger search box at the very least, you have the space to burn up there. (And a less offensive font would be great). Also, the light blue gradient makes the grey 3d-effect look nasty and crude, as do the white to light blue gradient buttons.
But in general, a completely clean upgrade as far as I can tell, and well done. Just need a little more attention on your graphic design/look and feel.