Sorry, did not try this one....
Since i never found what i needed with hosting providers i have tried out many different wikis and found "MoinMoin" to be my favourite to which i stick to for 8 years now ;)
http://en.wikipedia.org/wiki/MoinMoin
I drive my own (virtual) servers at HostEurope and Hostsharing.net with lots of wikis for different project groups. The problem with hosting your wikis yourself is that you always have to read the lists to fix any security issues, especially for public wikis.
I did not find the time to check professional MoinMoin-Hosters yet but maybe i should...
For me the most important thing about the wiki you choose is the syntax. Once used to it, editing the source with inline formatting is way better than any WYSIWYG-Stuff that messes of your content somehow. I love the Moin-Syntax but the syntax used at Wikidot seems usable, too:
http://www.wikidot.com/doc:wiki-syntax
I like the combination of Wiki and Forum, too! It's still not what i would call "real integration" of both worlds but better than what most others have. Unfortunately many folks are ony pro-forum or pro-wiki and reject the other side...