Is it worth paying for a structural edit?

We are putting huge efforts into finalising the manuscript of the latest book.  As the Itinerant Poet ploughs through the printout from 6-9am most mornings and I sit for hours processing the myriad of handwritten changes, I am once again at the point when I ask myself, "Will this one sell?"

Pros
It is about a dog.  People who like dogs buy books about dogs.
It is set in the 1970s.  Retro is good if you capture the atmosphere effectively.
It is written "by the dog".  Different perspective could be appealing?
It is humorous with elements of pathos (knock on effect of Itinerant Poet reading David Lodge books lately?)

Cons
If it is going to succeed, we may need a professional editor and that is going to cost some dosh.
It is written in episodes that are a bit like short stories with time gaps in between - not conventional.


Truth be told, we DID pay for a professional editor to look at a very early version way back in 2006.  The book was deemed to have potential and some very good points but needed work to be a success.  This was not an easy view to accept and resulted in the manuscript being shelved until 2012 when it popped up for a short rework to potentially coincide with the video release for the "Do the Dinosaurus" album. It never quite happened but here is the ebook cover I prepared at the time.  Any comments gratefully accepted.

For the first time since 2006, I have just re-read the editor's report and it now doesn't seem nearly as harsh as it did back then.  In fact, I can see what she was driving at AND I can see that the Itinerant Poet is implementing some of the changes even though he cannot remember anything much about the report.  Perhaps he has "grown" as a writer and it is showing through.

I recently read an article about the importance of a good editor to self-publishers (read the page at A Dystopian Future) and am now thinking that it may be worth laying out some more cash.  However, I will use the old report as a guide first and then look again.  I may even consider documenting the re-birth of the book via the blog and include some excerpts.  What do you think?

In the meantime, here is the video we made way back in 2011/12 that just happens to start with a bouncing retriever...

...NOOOOO that's not a bouncing (much) retriever, that's my backside!  Watch the next bit!