The 0.8" makes a much bigger difference than I thought it would, but I think its also linked to my second point...
... I've never previously bought a Smart Keyboard for an iPad, having had a Magic Keyboard and a couple of Logitechs over the years but never really using them. I've not had the Smart Keyboard Cover off this one and maybe that also makes the screen seem bigger because 99% of the time I'm getting the full screen without any vidrtual keyboard sliding over.
It's a big upgrade over my aging Air. Speakers sound great, the smoothness of the screen is insane and its clearly very powerful and snappy having played about with some video in iMovie.