I've had an interesting response from Adsense support. Obviously I can't quote it directly, but I believe I can paraphrase, or add short quotes Google would approve of being quoted.
I basically voiced my concerns about the advertiser drop-off before and since the QS algo, and gave them information showing them that the advertisers had mostly moved to YPN, and gave them some feedback I've had from one of the advertisers who has moved. I also asked the questions we have been asking about QS only applying to search, and voicing my opinions on that (politely of course - shouting at Google does not good). I was surprised to get an email back at all! I guess providing them with data or information they can go away and look at makes a difference.
OK - what they said was that "It is true that keywords which are inactive on search may still trigger ads in the content network." Note the word inactive. Probably means something or other.
The rest of the reply was without detail, but they did assure me in a very positive way that they are concerned about the adsense experience as a whole on both search and content. The other part of the email I think I can get away with quoting is "We realize we're not acting as quickly as you'd like, and when we say that we appreciate your patience, and willingness to partner with us for the long term, we mean it." They have also forwarded the suggestions (oft voiced here) of blocking by keyword and by advertiser on to the appropriate teams.
Now realistically I don't expect anything to happen on the blocking tools front. I'm sure that idea will end up in the shredder. For me, the key feature was the very positive way that they assured me that patience would be rewarded, and they are working on making content better but it all takes time. Normally the replies are very wishy-washy, or indicate that they simply don't understand the question.