Taking into account, of course, the fact that you have to do all of your own marketing. You have to make your novel stand out among zillions of other indie ebooks, all of which have the same low barrier to entry.
Just having a major publisher's name on it is pretty substantial marketing. Even more so if they go to the expense to print out a physical book, which is a large sunk cost up front. That tells readers that somebody believes in the book, to the tune of a few tens of thousands of dollars. And that publisher will generally get it into meatspace bookstores, where your book has to stand out only among a far, far smaller crowd of other physical books on the shelf.
It's not impossible to do very, very well with an ebook. But much of the time that additional 45% you get to keep is 45% of a much smaller pot. (And generally the margin is much wider than that, in fact. Going rate is usually in the 10-13% range, in my experience.)
The way I see it... if you can get a publisher interested, you probably should, at least until you have a large fan base of your own. It's the easiest way to that fan base. Building it up yourself is difficult. Not impossible, and possibly no harder than getting a publisher to take an interest in you. But if I had a publisher on the hook, I'd keep it.