One of the viewers growing in popularity is the Singularity Viewer. As Phoenix nears the absolute end of its useful life a number of its users are switching to Singularity. Often those with older computers prefer to go with Singularity for faster frame rates. Plus it has the look and feel of the SL Viewer 1.23, the V1 user interface.
Build 4114 is the version with SSA, Server Side Appearance, the avatar baking change planned to fix bake fail. All versions before this one will soon stop working, well stop rendering avatars. They will appear gray. So, this is going to be a required upgrade for all Singularity users. That’s required in the sense of, if you want to see avatar clothes then you have to upgrade. If you don’t care about that, never mind.