A fair guess would be that border entry will remain valid, as you hold an issued visa for the duration, but the +180 day extensions are a likely point of incountry control.
Yes I wanted some clarity.. I fully expected them to not know or guess, and prefaced it with 'I expect this is a little bit new but...' and she scanned the visa immediately knew what a DTV was and seemed very sure.. Also knew about LTR.. So was on the ball.