Also possibly an option to not upgrade every tier with shift hold, but only anything on the whole thread that's the same same as the initial selection.
What I mean is that if I select a yellow belt and the thread has a red belt somewhere else, DON'T upgrade the red to blue, keep it as red. https://streamable.com/l6hf08
The lane balancers are treated the same as splitters -- i.e., the option is to upgrade them as well, not whether or not the network building stops afterwards. Making an option as you describe in the video probably isn't impossible, I'll have to take a look.
Similarly, upgrading only those that are of the same tier will require some investigation -- I can see the use cases, but they are very niche.
