I’ll second the recommendation for clustering the operational and DW SQL instances for the reasons Wilson provided. I’m not sure I’d try to add the ACS database to that cluster though. With the cluster you increase availability more than simply having vm clusters in place. SQL clusters still (in my experience) failover and recover faster than waiting on a reboot.
ACS can definitely be a hindrance in an OM environment as it’s very demanding from a storage perspective, plus the overhead of managing all of that data. Be prepared for a large database!