If you are going to do OS virtualization, you should get Intel® Virtualization Technology for Directed I/O (VT-d) : this will improve security, reliability and performance by providing Hardware access to the different MOBO components for the VM's OS.
The "K" don't have this feature.
If you need extra security, either at home or at the office (I wonder why some say that you don't require security at home, who knows if you do some work at home and if your personal context requires security), you should get Intel® vPro™ Technology. Note from Intel : is a set of security and manageability capabilities built into the processor aimed at addressing four critical areas of IT security: 1) Threat management, including protection from rootkits, viruses, and malware 2) Identity and web site access point protection 3) Confidential personal and business data protection 4) Remote and local monitoring, remediation, and repair of PCs and workstations.
The "K" don't have this feature.
If you need safer computing with applications running concurrently, you'll maybe require Intel® Trusted Execution Technology : it's a versatile set of hardware extensions to Intel® processors and chipsets that enhance the digital office platform with security capabilities such as measured launch and protected execution. It enables an environment where applications can run within their own space, protected from all other software on the system.
The "K" don't have this feature.
In short, Intel tells us that if we are an IT developer, or simply someone who requires strength in security/stability, then we can't (and should not) OC the damn CPU... But if we want to do some OC'ing, then we cannot be a serious IT dev.... Which IMHO is a VERY far-fetch and ridiculous marketing assumption from Intel : it implies that one must be rich enough to have both worlds under hand, ie. in two distinct computers each having the correct CPU (one with let's say the i7-3770K CPU, and the other with an i7-3770).