Sorry for deviating from core Beta testing, but there are some things that slows my workflow down on a daily basis. I imagine others experience the similar.
When I create a new section, if I want to add a background image (usually a subtle pattern) to it, and if the same one is on a section nearby, I usually right-click on the image and open it in a new tab, and then copy its name portion from the URL. I have a Chrome addon to do it, but it is a long way.
I do have naming conventions for everything, but that doesn’t help much across many websites. I simply have to check the image name to search for it in the gallery. 
I am not sure how difficult this could be to make, but inside the inspector, if there was an area near the image or the background to click to get the image name copied to the clipboard, that would be awesome.
With patterns, we need to click Repeat > Both. This means that the default size Cover makes no sense anymore. Instead of it staying on the default Cover value, It would be great if the image size in px was inserted to the Size field, replacing the Cover value.
Alternatively, the Auto value does the same thing. This is perhaps even a better solution: you could add a dropdown to to chose from Cover, Contain, Auto, High-res. (High-res would insert half of the image’s width). In that case, if Both was selected, the dropdown could automatically switch form Cover to Auto.
One of the last bits of custom CSS I continuously use is for the mobile Hero background images. The desktop one is simply too big and heavy for mobile and I need to replace it with the smaller one using Media queries. I believe you had a good reason not to make this part responsive like the rest of the controls, but if there is a chance to do it, it would be amazing.
Thanks!