Are you running the latest version of Infix which is version 7.4.2? We have changed the behaviour of this version with regard to this issue.
In a majority of cases when using version 7.4.2 you should say no to this question unless you can see that text has disappeared when you start editing the text. If you say yes to this in a majority of cases then text that was purposely clipped by the PDF author may become visible.