Q: Should I deploy KB 2775511 to my Windows 7 SP1 and Windows Server 2008 R2 SP1 servers?
A: Definitely! KB 2775511 is a post-SP1 update rollup that contains 90 specific hotfixes (that actually contain other hotfixes, making the actual number of fixes much more than 90) for Windows 7 SP1 and Windows Server 2008 R2 SP1. These fixes also contain many performance and system reliability fixes in addition to a completely updated network stack, so they should be deployed.
There are no role updates or kernel changes, so any compatibility impact would be minimal. This is really targeted at enterprises, so it won't be distributed through Windows Update.
There are two specific features that need to be manually enabled and are documented in the KB.