A recent upgrade from SAS 9.1 to 9.2 necessitated an upgrade from Enterprise Guide (and Add-In for Microsoft Office) 4.1 to 4.3 for one of my clients. Disappointingly, the EG and Add-In upgrades didn't prove to be the smoothest, and the experience was painful for a significant number of users. Top issues were a) poor migration of EG projects, resulting in users having to re-write some of their projects, and b) Excel freezing when the Add-In was used and the session was left for 15 minutes or so.
As a result of the foregoing, I took more than the usual amount of interest in hot fixes. My usual approach to hot fixes is "if it ain't broke, don't fix it", i.e. I only recommend the application of hot fixes if there's a specific issue to fix.
If you have an interest in hot fixes, the SAS Hot Fix Home is an excellent one-stop-shop for this information in the SAS Support web site. From there, you can choose your version (in the left-hand column), and then select "All SAS 9.x Products" to find a comprehensive list of SAS products with hyper-links to hot fixes for those individual products.
We're now running EG and Add-In with hot fix 20; our users are much happier.
Contrary to the experience with the SAS clients, the deployment of SAS 9.2 Grid has been pain-free and the users have no complaints about performance or reliability/availability. My clients have a robust, scalable SAS service.