I used to greatly discourage independent editors, even just last year. I used to claim they were a waste of money because an independent editor doesn't guarantee your novel's going to get published. Instead I recommended wonderful beta readers, because if you can find the right one, they can be just as good as an independent editor.
Now here I am writing a blog post on praising independent editors and what an extremely useful asset they are to the world of publishing. Perhaps I'm being biased because I get my IE for free in exchange for my intern services (no monetary payment involved. Good. Because I only work 20 hours for every paycheck I earn twice a month). But seriously, the critique I received on my first chapter was something beta readers never ever pointed out.
First, I want to clarify that my beta readers aren't bad at all. In fact, they were excellent and I am EXTREMELY grateful for what they've done for me. Beta readers are wonderful when it comes to finding out just what type of audience you can target for your novel, and whether or not you have the interest of the average person. However, they don't always have the knowledge of what's actually going on in the publishing industry and what's going to sell versus what's not.
My IE actually does, and so her critique stemmed mostly from what agents are looking for (and a little of her personal tastes). Beta reader critiques generally stem from their personal tastes. 90% personal and 10% by the book. Heck, as an aspiring IE myself (or editor of a pub house), my critiques are still 90% personal and 10% by the book, but the feedback my IE is giving me is slowly changing that. See? She's even useful for my dream career. Not only am I learning to improve as a writer, I'm using her feedback to improve as an editor. A little job shadowing, I suppose.
Okay, so I'm super glorifying IEs when I know people out there who have been accepted by agents merely through beta reader feedback alone. Everyone has a different view. Most of my beta readers seemed to have enjoyed my original chapter one, but I took my IE's feedback to heart because she had a point. My chapter one, though it may appeal to a certain group of people, had no marketability, no reason for an agent to want to keep reading. I mean, there might be an agent out there who'd enjoy it, but I want to attempt to appeal to as many as possible and not just receive a partial/full or two here and there. I want partial/full requests from a variety of agents.
So this is where we get into some serious gray area. As I've said before, I know people who have landed agents with just beta reader feedback alone. However, I don't think I can be one of those people. It might be because my story, as my most recent beta reader pointed out, is radically different from anything she's ever read, and she's years older than I am. So because this story is different, it's probably safer for me to receive the feedback of a professional rather than the feedback of someone who doesn't always have that leg into what's going on.
All in all, use your judgment when choosing whether or not to go on beta reader feedback alone, or to choose an IE. IEs can get pricy, but a good one is invaluable, as my IE is.