There are very good reasons to go for SPAN / port mirroring to get the traffic you need to troubleshoot network and application performance.
Virtualization is widely spread and raises some new challenges for network analysis and network based APM. To analyze and troubleshoot performance degradations in application chains, which are partially or totally virtualized, you need to capture virtual traffic (i.e. traffic between virtual machines that does not go through the physical network).
We have noticed an increasing demand for SMB / CIFS troubleshooting. SMB/CIFS is widely used to access and store files for both user activities, and as part of application chains. It has become critical in numerous environments.
Every organization has to handle degradations and complaints regarding IT performance.