The features we need are these and only these: 
  
- Pay for and assign a container based on image. 
- Assign new containers to specific IP's and run post-installation script. 
- Start/stop/restart containers. 
  
I noticed that VNC doesn't work, that doesn't really matter as we manage the servers for clients. 
  
If this can be handled, we will go with Blesta - we have had issues with WHMCS since the start and it's very hard to manage.