for our agent protection we choose the policy based approach, because many devices are not always online/reachable and therefore we can't use the server concept. By using the policy approach you will loose some really nice features which have all been described in the forums except the ability to start backups from the b&r console and this is something I would like to have.
Of course, you could start psexec to connect to the remote machine and then start
veeam.endpoint.manager /backup
to start a backup session but this isn't as nice as using the well-known-approach within the console: right-click onto the item and then choose between "Active Full" and "Start". I think that communication protocols between server and agents have already been implemented so this extention shouldn't be that much costly to develop
yes I think it's ok that the job fails when there is no direct connection to the client. Alternatively, you could put the "backup request" in a queue and when client comes online again, it'll receive the command