Sorry but this is not correct
16 distributed switchs maximum per virtual center, not per host.
you can have 64 hosts per 1 distirbuted switch..
When using DVS you have to change your mind set. With stardard switch(VSS) you pretty much created a switch for everything to seperate. You do the opposite now with DVS you create one DVS and have multiple port groups for speciliazed functions.
The only true reason to create a new DVS is cross datacenters, DVS is datacenter centric, so if you have 4 hosts in one Datacenter inside of VC you cannot add hosts from another datacenter to that DVS.
This factor becomes a limiting factor.
Google "configuration maximums vmware 4.0"