Include the ability to assign application associations per workset, so that files cannot be opened in the wrong version of an application. Each workset at a site can use various application versions. With multiple versions of applications installed, the only way to open a file with the correct application version is to use "open with." This leaves a lot of room for user error. Opening a file in the wrong version of an application can cause data loss. Even with the pop-up warning, it does not prevent users from opening a file in the wrong version.
I request taking it a step further, and also include the ability to assign application associations directly to a file.