I have a test set of 4 each (2 fletched, 2 unfletched) ACEs of 520, 570, 620, 670, 720. All with screw-in points to allow optimisation of point weight. All about 29". You're welcome to visit & do some tests - if you're up for a trip to London.
Of course, TimidToad would tell you that it's possibly to get several different spines to work well with the same bow. I know my bow will tune well with ACE 620s or 670s, and maybe other spines either side too. All I have to do is use different point weights, button pressures, etc. etc. Have you tried upping the point weight on your 570s to the max recommendation by Easton, or even a bit more? That would make them behave more like 620s (and they would carry better in windy conditions).