As a result, I need to check the incoming and outgoing dates and set appropriately for the users local time, and so the server perceives it as the appropriate time / date, especially important when the data is being used outside of the flex app, only.

Here is a cut / pasted example of my utilities:

/**
* I convert dates from DB / fluorine conversion
* to the appropriate time to be used on the
* client side app. The reason i am required
* is due to a bug between our data servers and
* the fluorine date conversion that implicitly
* attempts to convert from UTC to local time
**/
public static function setDateOnGetFromDB(localDate:Date):Date{
var offset:Number = localDate.getTimezoneOffset() * 60 * 1000;
var UTCDate:Date = new Date(localDate.getTime() + offset);
return UTCDate;
}

/**
* I do the opposite of setDateOnGetFromDB
**/
public static function setDatesOnSendToDB(UTCDate:Date):Date{
var offset:Number = UTCDate.getTimezoneOffset() * 60 * 1000;
var localDate:Date = new Date(UTCDate.getTime() - offset);
return localDate;
}

really your best bet is to either store epoch offsets (ms since 1-jan-1970 UTC) or do as ted suggests & use UTC.

i suppose you could try pushing this back on the db server (eg sql server):

SELECT dateDiff(s,’1-jan-1970′,yourDateTime)*1000. as testDate
FROM yourTable