I would request an evaluation license which gives you access to the supported repositories for a certain window of time. When we started down the journey of Grommunio we had already been using Zarafa (Kopano) and also evaluating Google Email, Microsoft O365, BlueGensis (straight postfix/dovecot) but in our Customers cases the limiting factor were mailbox storage (have mailboxes as large as 100GB+) and uptime. So far we only use the appliance under kvm models but will be looking to implement HA in the future.
