While there is a reasonable amount of information about how HA works in vROps I have found there is still some confusion as to how HA actually works with vROps or rather what are the benefits and perhaps more importantly the cost for enabling the feature.
HA is a great feature and in my opinion should be considered seriously with any deployment (where possible).
Not only does HA protect your Master node (which essentially behaves as an index for your vROps cluster and if lost will render your cluster dead unless you have a working backup of your cluster) it will also allow your cluster to tolerate a data node failure. So in short what is not to like!
The important thing to remember here is the cost in terms of object/metric capacity for your vROps cluster and in turn the additional nodes and or hardware you may need to facilitate/provide for having a HA enabled vROps Cluster.
If you have deployed vROps before then I would hope you are already familiar with the VMware provided vROps Sizing Spreadsheets When you input your environment figures you will be informed of the size of nodes and number of nodes required to monitor your environment. Furthermore you can select how many months you plan to retain data and whether you will enable HA or not.