Hello!
I happen to be both a RIPE member and the current chair of the ICANN Customer Standing Committee that audits the PTI when it comes to its performance as administrators of the DNS root zone.
I'd just like to concur with your assent for the PTI and their work to fulfil the IANA contract. See this as a "+1" from me. Your summary matches quite well what we in the CSC see on the domain name side. We see "100 %" all over the field, with only the occasional minor breach. Those are counted in the singles, and in most cases it's down to SLAs that weren't thoroughly tested before being put into operation.
We also find the PTI very approachable and accomodating, and we have a very good dialogue with them.
If you and the NRO community share my positive views, I hope you share them also with the PTI. It's easy to forget to convey appreciation for good work and to focus only on criticizing when improvement is needed.
Best regards, /Lars-Johan Liman