Congratulations on your new arrival Rod.
The hole in the data set is due to the hole in the autocollimating flat, not to do with the interferometer.
Rememeber to allow some artistic licence in the Strehl number on a large thinner mirror as the astigmatism co-efficient is subtracted from the data. As the vertical mirror bend with horizontal axis alone, would lower the Strehl into the 0.70's without adding the complexities of momentary air movement and mirror seating and any real astig present. As always it comes down to the experience and skill of the optician for a good optic, there are no simple solutions to proving how good a mirror is on paper, just eyeball at the telescope in the end.
Enjoy, and look forward to seeing your SDM at SPSP.