So, there appears to be a significant piece of documentation missing from Major Releases of IDM.

There needs to be a documented list of Driver Shim Versions that will be installed as part of Major Releases.

If a customer is proactive at maintaining Driver versions, it appears to be very possible that a Major Release (such as the long awaited 4.6) will end up downgrading driver versions. Without a full list, it makes it extremely time consuming and painful to determine what post-patching is required.