Traffic shaping, vsan

Our infrastructure team are looking to configure and enable distributed v switches, aiui these give you the ability to run QoS across the SAN, traffic never has to hit the core switch.

My question is, assuming the QoS on the SAN is configured correctly, is it worth applying it to our core switch? And if yes is there recommended traffic types to QoS i.e iscsi?

I'm more than happy to RTFM, is someone can point me to the most appropriate manual ;)

Thanks

Rich