Raffi,
Yes the EVPM could be set to do 5 migrations at once by setting the following setting.
ConcurrentMigrations = 5
With this set, EVPM will spawn 5 migrator processes from a single initialization file.
This makes the set up and running of parallel processes simpler. The maximum value allowed currently is 5.
It is recommended that the number of parallel PST Migrator processes/threads is set at 5.
So they are both single threaded, by setting the ConcurrentMigrations or running multiple instances of the wizard you are able to get more throughput.