Licensing: Can vCloud Suite Enterprise license be downgraded to Std?

I am designing for a customer that has vCloud Enterprise Suite licenses.   Only some of the clusters will use enough of the features to justify vCloud Enterprise Suite licensing.   Since I already have more Enterprise CPU licenses than needed for the initial roll out I am wondering if I can license all hosts using the vCloud Enterprise Suite licensing and then later on purchase vCloud Standard licenses and downgrade some of the clusters Std.

Can I do this?   Any potential issues?

Thanks,

-MattG