I recently went to a talk by Polly Courtney who explained that she had decided to self-publish with Matador after being frustrated by her treatment by conventional publishers. Courtney, who estimates having sold 100,000 books in all, explained the fascinating story of how she became a writer after collecting anecdotes about the cut-throat world of city banking when she decided to quit, which was later made into the book Golden Handcuffs. She wrote her first books whilst still working part time as a consultant.
She explained how a structural editor suggested she should transform her book from fact to fiction, but then other editors did not like the banking aspect and wanted her to transform her book to a book about how a banker shops. She was unhappy with the titles and covers of her books. She discussed the difficult balance between acccepting the advice of experts and going with your own gut feelings. Structural editors, she explained, could give you advice on how to structure a book, in contrast to line editors who checked facts and suggested changes in grammar and sentence structure.
It struck me that Polly was in a much stronger position to have the luxury of going it alone after she had had already made her name with the support of the conventional publishers and that her initial decision to go with a conventional publisher was quite a wise one, even in the light of events.