Paid, Permanent, and Plus S2 accounts: Comment pages display in the chosen site scheme by default; you can also enable custom comment pages that match your journal's S2 style.
This is not true. In most layouts, the customized comment pages are enabled by default - so that if you switch to paid/plus, you immediately have customized comment pages, and instead have to specifically disable them if you want regular site scheme. (Variable Flow is an exception to this rule, as its comment pages were unfinished, and therefore the option was turned off by default. When the comment pages were finished, the option was left off for backward compatibility ;) )