I’ll pass the suggestion along to our community guys who make the release notes. I just checked on the last update to FBX 2014 back with version 4.2 there was a bigger notification, but it also listed some issues it directly fixed. I’m not sure if that was the case, but it could have been since there have been a couple of years between the two.
As for the differences between 4.9 and 4.11 there have been some significant changes to the FBX importer with UE4 since these versions are ~6 months or more apart in the Change lists.