We do not mix platorms, a given AS instance will only be used for production, qa or dev
The issue about resources is you don't want to run 30 seperate jvms, each with their own memory allocation to run a production and live copy of an application for different 15 clients in a SasS enviornment. This would be hidious micro managment
The CLI approach works, but it fells like a work around. An enviroment should be able to support any ears i choose to deploy, you shouldn't have to change the server just because you have a new SaaS customer