Just in case anyone else happens upon this thread: we typically have versioned feature classes with Editor Tracking enabled. We have recently started to implement archiving. Our editor tracking timestamps are in UTC and our archive table (_H) timestamps are in local time.
However, it appears that for nonversioned data, the archive timestamps are in UTC rather than local time. (Editor tracking timestamps are still in UTC as well.)
This is on 10.4.1 with an Oracle back end; YMMV.