If it helps, I am pretty skeptical ED provides a generic “opportunity” to all applicants.
I think where it can be a very good idea is if your top choice is the sort of college that might practice yield protection, and you are qualified enough that it is plausible you might be a “victim” if you applied RD.
The basic question is whether they would think you would very likely get offers you preferred, in which case they might like you in theory, but waitlist or even reject you thanks to thinking they can’t get you. And if that isn’t possible, because they are your favorite, you can prevent them from doing that by mistake by applying ED.
LIke, suppose you told me your top choice was Tufts. I don’t know the rest of your profile, but a 1560 is well above even their 75th SAT (1520). So again without knowing anything else, we can imagine you are a plausible risk to be yield protected if you RD at Tufts. So, you ED instead.
Then maybe Tufts doesn’t actually want you, and you get rejected, or they are not sure, and defer you to RD. But maybe they do, and there you go. You get to end the process early and go to your favorite college.
By the way, though, if you apply ED and Tufts doesn’t actually want you—why would applying ED help? I think that is what people sometimes want to believe, that applying ED will take someone a college wouldn’t normally want to admit and will turn them into an admit. But that makes no particular sense from the college’s perspective. ED admits make sense when they know they want you. If they know they don’t, they just reject you, and if they are unsure, they can defer you.
OK, so EDing a college which is your favorite but might yield protect you can be a good idea, but you don’t have a college like that, not yet at least. So for now, I wouldn’t be considering ED anywhere.
You are right REA at places like Princeton isn’t the same thing, which is basically because Princeton isn’t ever going to think it has no chance of landing you, 1560 or not. But if it works, then either you are done early, or at least you can cut your list to just colleges you might like better than Princeton.
As a final thought, there is of course ED2. Like if you REA Princeton and they reject you, maybe at that point some college with ED2 does stand out to you as your favorite. Or not, that’s fine too. But you don’t have to decide this now, and in particular I would again discourage thinking of ED2 as something that makes you more desirable, as opposed to avoiding them yield protecting you.