The functionality we would love to see is the ctrl+click/shift+click functionality for selecting checkboxes more efficiently. The reason for this is in several use cases, our users will have 100+ items to select under a single parent. In many cases, they will need to select about 1/2 of them. So the only option at that point will be to select all 50 or select the entire parent and 50.
Having a mechanism to more efficiently select/ (such as shift+click) would be ideal.