The datastores backing a cluster should directly map to that of a Storage Profile, as assigned to vCloud Director.
Storage DRS should be fine, as long as:
1. you are using vCenter 5.1 + ESXi 5.1 + newest VMFS (needed for Linked Clone awareness)
2. you state that Storage DRS should keep all disk files together. vCloud only supports a VM were all VMDKs are on the same datastore
3. know that Storage DRS will not move a disk outside the currently set storage profile in vCloud Director (hence the first comment).
As far as I know, if you meet these requirements .... I think it should be okay. I would definitely test in a non-critical deployment if possible.