OK.
Actually it doesn’t work with VEP 6.
I uninstalled version 6, and now VEP 5 recognizes H6 as H5 when I change its name.
Now, individually saved channel sets load with H6.
BUT, my existing VEP project (Metaframe), and this is the most important, still doesn’t load previously created channel sets, using the newly renamed H5. 
PS : I renamed HALion 6.dll to HALion 5.dll