Hi Sean.
It's good to hear that your Omni 4000 worked out well for you.
In regards to an airbrush for freehand camo, the next step up in terms of atomization and precision would be the Badger 100 series.
I would usually recommend the Badger 100LG, but since you want a smaller color cup then the 100G would be your best bet.
It comes with either a fine, medium or heavy tip and needle and I would recommend the medium set for acrylics and enamels.
In all honesty I don't think the Badger 100 atomizes that much better than the Omni's do, it is just a slightly more refined airbrush and has a micro-tip system, whereas the Omni, as you know, has the single needle/tip combination. Freehand camo is not as difficult to do as some think and the Omni should have no trouble doing that, but of course if you want a new toy, then look into the 100G.
I hope this helps somewhat.
Mike
“Wisdom is the right use of knowledge. To know is not
to be wise. Many men know a great deal, and are all the greater fools
for it. There is no fool so great a fool as a knowing fool. But to know
how to use knowledge is to have wisdom. " Charles Spurgeon