@themattroyal – update on this.
Inline preview seems weird and doesn’t work for me. That’s not a big deal, just FYI.
Live Preview. Clicking that is going to the hope page and adding a query string of ?preview=true. Cool, but as soon as I click through to my actual shop page that string goes away and the preview ends. I did find that if I manually append that to my shop pages it works. That said I’d recommend using a query string less likely to conflict with other maintenance/preview plugins.
Banner issues:
This is an old theme, not built by us and going away, so they could have done stupid things… but FYI this is what I see logged in:

Notice is under WP Admin bar.
Then in incoginto I see nothing because we have WooCommerce Store notice of our own showing a sale, that completely obscures the maintaince notice under it. Maybe a high Z value to make sure it shows?

Hi Jon
Thank you for the thorough feedback.
The preview modes were developed for testing of the popup windows or notices to preview the content and visuals of these.
But I like your suggestions and will give some more thought to your ideas and some other possible improvements here.
Ultimately the best is always just to test in an incognito window but some users aren’t as clued up and get confused, forgetting they are still logged in and then functionality seems broken when infact its not.
I will release an update shortly increasing the z-index to prevent the notice falling under any other notices.
Thanks again for the feedback, its really cool of you to take the time to this 🙂
Most welcome. It’s cooler you put this into a plugin and release it 😉