A good editor is invaluable when starting out. Later on it perhaps depends on how complex the story or writing is. Editors can be looking for similarity not originality. The final script a poor representation of the original story or article. An article of mine, which was picked up by Wikipedia for its originality and informative ideas was given forty edits from around the world! It was like a mechanical invention rather than an interesting article in the end!
You know, Rob, I’ve learned people offer their services for pay for a variety of reasons, and they live in a variety of circumstances. Some do it just to make a little side money, because they love the creativity…it’s not everyone who’s doing it because it’s their main livelihood. Others are new to the field and don’t feel they can command more. And sometimes, maybe you connect with someone who’s affordable, but they still do a great job.
The other thing I really like is your breakdown of the types of editing available. That’s what I find needs to be explained the most. Especially in business editing, you get scenarios when someone thinks a document needs “a proofread”, when it really needs a copy edit or even a heavy line edit, and you have to justify the cost or the time it takes to complete it.
Rates – Most online book editors are freelance editors, which means they set their own rates. Editors may charge per word, hour, or project. Editing is a valuable investment in your book as a good editor can turn your story from meh to amazing! But the highest rates don’t necessarily mean the best editor, and the lowest rates could be wasted money. Definitely take rates into consideration, but don’t select an editor solely on price.
It is not the best option. A program will never beat a good editor. The only thing I suggest is that a writer uses a program to help as they work or write. This helps make your book cleaner and causes less effort on the editor – making them happy and if done well enough, could cause your rates with the editor to stay lower or low. If you have too many issues, an editor may demand more.But if you just cannot afford an editor, then the best way is to use a program, and have you do a full read through, and have someone else (friend) do a full read through…and the more the merrier.
As for multitasking, believe it or not, I try to schedule so that I am only working actively on one book at a time. Research keeps showing that “multitasking” is actually less efficient, because of the time lost to leaving behind one task to restart another. (Think of it this way: If you take on two clients at once for work that would take one week each with your full attention, either you can tell both clients the work will be done in three weeks because you’ll be alternating between them, or tell one client it will be done in one week and one that it will be done in two weeks, because you’ll complete one before you start on the other. Which of those makes more sense?) Obviously, with back-and-forth communications, sometimes complete “monotasking” is impossible, but I think it should be considered the ideal.
While you may (or may not) be correct in your assumptions, your tone in general is rude, and disrespectful. If you are indeed a true editor of distinct taste and experience, you should not feel the need to bad mouth others for their thoughts and opinions. Show a little decency, and realize that you are indeed speaking to a human being, who probably has thoughts and feelings, and is in my opinion, a much more intelligent human for having the intellect to not attack someone verbally for their thoughts. No one needs you to be rude, or asked you for that matter.
Perhaps there is some misunderstanding of the phrase ‘developmental editing’ used in this article. Given the number of hours necessary to process, dissect, and reconstruct a text of that size, it sounds like anyone who charged that lowly is doing the job for fun and has a spouse to provide for them–all the while devaluing the work of people who do this for a living. It’s really not ethical.
At first, I didn't want to add Fiverr to this list because there are a LOT of editors on Fiverr that aren't exactly a good investment.  But, that doesn't mean there aren't amazing opportunities out there.  Editors like Kerrie McLoughlin, have done an amazing job with their Editor Fiver gigs.  However, if you do decide to go through Fiverr, then ABSOLUTELY use my test to ensure you aren't hiring someone who isn't qualified.

Next, it is possible to follow the road to traditional publication without hiring your own editor, with editing being done at the publisher’s expense. However, you have to be a very good writer and self-editor to get on that road, and what you write has to fit into a very marketable niche. You also need to be very patient and willing to weather plenty of rejection along the way. Don’t jump too quickly to the conclusion that this option is closed to you. Do your research carefully. There may be a small press that is just right for your book and that will be happy to help you make it the best it can be while paying YOU rather than making you pay them.
Regarding your last question, I know of no editor who gives a money-back guarantee for occasional errors that happen to slip through or for a different opinion by a later editor. I’m afraid such things are just the nature of the publishing beast. But by having a shorter portion edited first, you will get a decent feel for whether someone is the right editor for you, and will be able to be confident in his or her work on your entire book.