Yes NGC have created a mess, a false market for many "so called" varieties because they are too lazy. They refuse to listen to people like me. I've put a lot of effort into this reference to hopefully remove the confusion with regards to varieties, PCGS have been very open regarding it but NGC rude and dismissive to be quite frank.
Yea the software is amazing, this is a WIP but really quite cool, digital albums https://www.pcgs.com/setregistry/europe/great-britain/british-victoria-sovereign-date-set-circulation-strikes-1838-1901/album/191325
PCGS have been super welcoming to the reference being created here, as it actually improves upon existing. I'm speaking with the software lead and we are on the same page with creating features better for the collector, not for money, which seems to ruin so many other areas of the industry.
I only grade in the US with PCGS, I found that any coins I purchased on the open market that were graed Paris were as you say overgraded, they like to give MS62 to all shields for example regardless of the coin!. This is well known though and luckily the cert numbers are different so easy to spot, at least they were at the beginning.
I think what matters to each collector changes through their journey, but I honestly feel that when you get towards the pinnacle of Sovereign collecting that you'll want to be with PCGS. It won't be long now before they have UK offices or even graders, I've had discussions with the now president about this and they want to make it happen but it has to be profitable with them. I really hope they do not use a dealer for the service (which is on the table), but do it themselves.