Update - all files have gone up.
I left the phone running over night and finally, they have gone from 800... to all being up there.
Yes I now understand about iCloud, as it's not for images.
I can now see all images on both devices, and I can see how to access them via iCloud, which is useful if I Want to show a pic, and save it to a friend's PC.
Initially it was the speed issue. 2 hours and nothing, but it seems that the figure shown, is not "real time". It goes down when it updates. So whereas it may have been 834, it could have been down to 700. At the time I didnt' know to check icloud.com.
Time will tell how useful I find this.
But so far it's ok, as if I am using my iPad I can show all photos, without having to scan through Dropbox.
Question: can you create folders in Moments, so for example, "Holiday in Dorset". Can you do that, so those folders are on all devices?