That test was very informative, sort of reinforced my own observations using Vallejo and Tamiya. Their results correlate to some of my paint observations.
I believe Tamiya has a lot of pigment, but a weak binder, so it dissolves easily with most cleaners, thinners, or re-brushing, but will dry fast and can be masked after an hour or so. It tends to scratch easy, especially matt finish, and definitely needs a final clear of some sort. Definitely will stick to plastic without any primer, I even sometimes use it as a primer. When wet, its fairly easy to clean out of the airbrush with alcohol.
Vallejo, is a very slow drying paint that ultimately dries rock hard and will not scratch or rub off easily. Definitely needs a primer, but once its dry, it hard to affect it with a solvent or scratching. I have switched to using Windex blue for cleaning my airbrush, its very effective (don't use other brands as they tend to use a blue dye that stains).