I wouldn't fully 'clone' it, as a snapshot should do the job. After a day delete the snapshot.
Ideally you'd also be doing a VM-level back-up on some sort of schedule to allow a roll-back if necessary.. mind you this runs as a incr or diff to cut down on IO.
I don't explicitly recommend a clone because it's overkill given the 'size' if the vC Ops appliance and the effectiveness of snapshots for rollback.
Snapshot is the best way to go, I've recently completed (vApp + OS SLES 11 SP2) upgrade to 5.8 using snapshot.
But incase you still want a clone of both UI and Analytics VM's, power down the vApp and take a clone.
Thanks guys.
Greetings.