How easy have you found the whole process, as something of a novice? It seems like the whole process is actually surprisingly quick, if you discount drying times. And, strange as it seems, maybe less brush work isn't necessarily a bad thing when painting?

As am I! Little by little though. Enamels have a much lower entry point, and require less in the way of a setup - the airbrush will require a little more time unfortunately.
If nothing else it would look a little odd for his armour plating to be damaged, dirty and rusting, but his feet sinking into the mud and squeaky clean

Just give it a mock up, see how it fits. =]