Would be cool if when pasting onto inserters, and the inserters have the same item as the pasted in logic, the item count is added to the current logic instead of overwriting it. E.g. having 100 gears as output, pasting it again would change it to 200, then 300, etc... It would be useful when only a stack of items isn't big enough of a buffer.

Check out Additional Paste Settings https://mods.factorio.com/mod/AdditionalPasteSettings

It's capable of doing this out of the box I believe, along with a lot of other features, and might work better for you. I mainly made this mod because I wanted to keep it simple and didn't want the extra stuff like the stacking.

Cool, thanks. That mod looks quite complex, gonna take some time to get used to.