Are you asking if there is a better way of doing things? If GTM is better than an iRule for geolocation? The short answer is: no, not really. The longer answer is: There are times where each would make more sense, and if you want to describe how you're doing things so we can offer more insight, thats completely fine and we can have that conversation. It is much more a conversation about which makes more sense from a design perspective, though, and not so much from a performance or functionality stance, as those things will be all but negligible in difference.
-Colin