I'm engaged in a vRA 7 fully distributed HA environment with external vROs and the platform is not stable. While installation may go smoothly, HA is not currently possible due to either bugs in the vRA appliances or in the vRO appliances. Both embedded vRO and external vRO result in platform outages either randomly or when a vRO node is taken offline.
The behavior seen with the embedded vRO is that randomly one of the nodes will simply stop working. Then if you reboot the other node, you're no longer able to bring the environment online at all. This is due to the new load balancer rules that check the health of all services on the vRA appliances. Due to the appliance not being completely healthy (embedded vRO service isn't running) the load balancer doesn't send traffic to it. The other appliance that is attempting to boot can't start because vRO is unavailable and the shell-ui-app and advanced-designer-service services refuse to start until it is.
The behavior with external vRO appliances is similar, but slightly different. The first difference is that the vRO appliances don't randomly stop working as seen with the vRO embedded service. Also, because there is a separate load balancer VIP (and associated health checks) one would think that vRO can continue to run even if vRA is offline. Unfortunately that isn't the case because to assign licenses to the vRO appliances you need to authenticate using the vRealize Automation authentication provider. This would also be fine, if that authentication method didn't use the vRA load balancer VIP which requires all services on the vRA appliances to be running for traffic to pass to it.
So essentially you end up with an infinite loop because vRA requires vRO to be online for it to start and vRO requires vRA to be online for it to start. The only way around this is to disable the health checks on the vRA appliances temporarily any time you need to take either of the vRO nodes offline (or one goes offline), and even this sometimes doesn't work and requires you to then restart the vRA appliances for it come back online. Ultimately this results in unplanned downtime.