@kevinrm Patience ran out
The message finally arrived, so we ran the 5.2.18 upgrade on our live store. Another easy, smooth faultless transition (the extra DS-Store file glitch is still there but it's easy to solve) We'll run live like this for a while now.
Being on a roll, we then ran a dev store 5.2.18 > 22.214.171.124 upgrade and again, another easy, smooth faultless transition. Nice! Our 5.2.18 > 126.96.36.199 upgrade will be as close to 'vanilla' as possible we think, thanks to our own choice of how we are applying customisation. So it's only right that it was as smooth as it could be.
Now the hard work of manually converting all our customisations / alterations etc into twig (all of which are contained within /skins/custom_skin) so that this store looks like our 5.2.18 live store
I am just going outside and may be some time...(sic) Captain Oats
You can see in our sig that our 188.8.131.52 dev store is running very well on PHP7 if that's of any help to you.