Every now and again, this comes up. It did again 2 Days ago on Dave Lawrence's Blog
I still feel that in spite of all the benefits and extra redundancy you get with vCenter as a VM, it still feels like putting too much of my precious eggs in one basket.
According to VMware - 60% of all vCenters are Physical - and 95% run of them use an SQL database.
Seems that the majority feel the way I do..