I'd like to see their a/b tests. Can you sign up another few email addresses and compare them?

We've subscribed to each of them a few times but never seen any huge difference between what we receive at any two addresses. Most differences we've seen are very small - like dynamically inserting someone's state or zip code.

What's the spam score out of. 0 to 1?

Great question, spam score is by Spam Assassin and there's no real cap but generally anything below 3 is relatively safe.