Setup a new ZCS OSE 8.0.0 a few weeks ago on a VM with 2GB of RAM. We tried it on 1GB previously but it seemed more hassle than it's worth with that much RAM.
Currently it mostly runs properly. We have setup ZPush successfully.
The problem is the mailbox seems to randomly crash after a few days or so. We don't have many accounts or much traffic going through it just yet, so I don't suspect it's a load issue.
The closest thing I can come to something tangible is the /opt/zimbra/log/zmconfigd.log reporting:
Additionally, earlier today when troubleshooting it I noticed there was a pid issue for mailbox, preventing it from starting. I verified the pid didn't actually exist by trying to kill it, then I moved the pid file aside (instead of deleting), and the service restarted properly. I then deleted the old pid file, but this odd crashing seems to persist.
/opt/zimbra/bin/zmconfigdctl: fork: Cannot allocate memory
Unfortunately I do not have monitoring currently going so it's a pain that I have to manually determine this, so it makes it hard to determine when it _actually_ goes down.