I am hopeful that I found my own solution. So the touch screen would function fine after initial install but as soon as I placed the cable cover on, lowered the screen and tightened the penta lobes it would start to act up- phantom touches, unresponsive etc. So I just took the cable cover/shield off. It's been about 24 hours and not a problem so far. Obviously not highly advised but I had a paper weight otherwise.
I figure the shielding might have been pulling on the connection to the digitizer which was the reason for the delay in the behavior. Perhaps the original cable had a prebent set of cables that is not available when you order in the repair market. Or maybe the issue was a result of the first repair shop being a little over zealous when removing the oem display.
The new 6s has just three cables to the display - unlike the four present here so perhaps it was a known issue for them as well.
Maybe an ifixit staffer can weigh in.
The only real lesson learned is : don't let a friend break your device.
Anyway, leaving this here in case some other poor b*stard has a similar issue and for general prosperity.
-bp
Typed on 6+ using ifixit replacement screen and hack repair job