Thanks Darksoul71, those are a lot of ideas.
The apt-get update upgrade install is exactly what i want to avoid. Bandwidth is of concern and reusing is a preferred option. Changes made are considerable. So, the installable media of in-use OS will still be better than basic iso. Diskspace backup is a solution, but is less pristine than an installable media.
I will look into the many approaches in the following days. Hopefully i will be able to find success in one of them.
