So I bought another 14.5 GSD in pieces at the black Friday sale (stripped upper, REBCG, ACH) to avoid having a pinned muzzle device.
It got here this past week.  Put it together with an SF3P.

Took it out today. In the rain, zeroed at 100yd with 3.5x ACOG TA11 with chevron reticle.

Last three 10rd groups with my 77gr SMK handloads:  without can: 1.125".  With Mini2 on it:  1.375".  Without can:  1.125".  In, I believe a first for me, I didn't observe any notable POI shift at all with the suppressor.

My 16" GSD is similar in terms of accuracy.  11.5" GSD is not quite this accurate but still noticeably better than my DD Mk18.  All beautifully gassed.  These uppers just continue to perform as the best in class AR15s I've ever owned.
GSDs are awesome.
That is all.

Thanks for sharing your experience, and I couldn’t agree more about  Geissele’s rifles and uppers…!