For my part, all I've done was update a single line to bring the code in line with our content security policy, but now that the genie is out of the bottle and we're running on a custom template, I'm looking to rip off the inspiration of others to make it do something more interesting..
It probably won't surprise you to learn that we do not normally recommend editing the utag template, as it makes future updates much more difficult :-)
If you have a useful enhancement, we would love you to share it with us so that we can look at incorporating it into a future release for everyone's benefit. I cannot think of any significant benefits that you could get from editing the tag template, and the risk of breaking things is pretty high. New features of utag.js are always made available in the release notes: https://community.tealiumiq.com/t5/uTag/utag-js-version-4-40-Release-Notes/ta-p/12946
If you (or anyone else) have ideas for improvements or enhancements, it would be great to hear about them so that we can consider adding them to the next official release of utag.js.
Thanks for your highly valuable input and feedback; we really appreciate it.
Breaking stuff is the best way to learn how not to break stuff in future.. :o)
Thus far I've tampered very little (and really, all I've done is implemented #6 on the 4.40 release notes early), but I had been wondering about adding onerror handlers to pixel trackers which might set localStorage variables that can be picked up on future events by another vendor, e.g. using an analytics vendor to track both the outcomes of total load rules on the page, and the subsequent success rate per tag firing.. though from the looks of things that's an edit to the tag templates too, bit messy..
Then a bunch of boring stuff around debugging, extending link() and view() with custom event types, changing the behaviour of utag.data with respect to utag_data such that they behave consistently regardless of whether utag_data is created before or after utag.js runs, etc..
Mostly I was wondering if anybody had done anything interesting with any customisations that made life easier, notwithstanding the obvious pain that upgrades then bring...