I've created a profile script which is taking an mbox parameter for 'Sign up date' (which is a text string: "yyyy-mm-dd"), and converting it into a number, whose digits are YYYYMMDD. The value returned in mboxTrace for my test account is ''2.0170713E7" (13th July 2017).
My hope is to then create an audience with criteria like "user.param IS GREATER THAN 20170728", or any others as and when they are needed. I.e., this is saying 'only target visitors who signed up after 28th July 2017'.
After testing, it doesn't appear to be working as expected. In some cases my content shows correctly, and others it doesn't, but it doesn't seem to correlate with numerical magnitude.
Is the 'greater than' criteria a sensible thing to use for user parameters, or are they always returned as text strings? If so, does anyone have an idea for an alternative solution?