Never mind the abuse: Save the whistleblowers

I've done an article for InPublishing about the moves by the Independent, The Times and Sunday Times to stop anonymous postings on their news websites.
On this site, I've already quoted the Independent's online editor Martin King stating: "Websites have been encouraging cowardice. They allow users to hide behind virtual anonymity to make hasty, ill-researched and often intemperate comments regardless of any consideration for personal hurt or corporate damage."
He urged posters: "If you are speaking up, then speak up proudly and with responsibility. Embrace this opportunity to come out from the cloak of anonymity. That’s for the cowards for whom “freedom of speech” is something to rant about rather than an expression to live by. With all its obligations."
Here are a couple of quotes from my article, which raise the question of protecting postings by whistleblowers and anonymous sources:
Steve Busfield, Guardian News and Media's head of media and technology, warned that stopping anonymous quotes would curtail whistleblowing. He said: "Removing anonymity from comment posting will undoubtedly result in a fall in user comments. If I were to be cynical I could point out that the Independent website generates few comments anyway (see its blogs page for instance http://blogs.independent.co.uk/ ), while the Times will already see a substantial fall in user interaction with the erection of its paywalls. "It might be that comments will become slightly politer if the mask of anonymity is removed. But does it really gain other readers to know the name of a member of the public posting a comment hundreds of miles away? Removing commenter anonymity will also make threads less interesting, less revealing. There will certainly be less whistleblowing."
Jo Wadsworth, web editor of The Argus, Brighton, said some of the most valuable comments on her site were anonymous. She said: "No system can guarantee real names, but only the most persistent trolls will go to the trouble of inventing personas to re-register - and shelling out for the privilege in the case of The Times.
"Having said that, most trolls like to develop a persona in any case, so I'm not sure that using a real-sounding name will make much difference to them. "However, some of the most valuable comments, news-wise, are left anonymously - tip-offs, personal accounts of traumatic experiences, etc. If I were implementing a real-names policy, I'd definitely want to retain a way for people to post these, even if these were post-moderated."