I believe I already answered you in an email but I'll throw in my $.02 here also.
![Big Smile [:D]](/FSM/CS/emoticons/icon_smile_big.gif)
The two you mentioned would be good together as one is a gravity-feed and the other a siphon-feed. The Omni 4000 is an excellent gravity-feed and is great for modeling and illustration purposes. The Anthem 155 is a great all-around airbrush that was designed mainly as a T-shirt art airbrush but is equally versatile enough for murals, automotive airbrushing and modeling also.
I think that maybe these two might be your best bet to cover all of the purposes you mentioned. If you want to buy only Omni's then you could go with the Omni 3000 in place of the Anthem as they are basically the same spraying wise, although they each have their own nice designs.
The Anthem 155 has the fastest break-down time of any double-action airbrush in the world too.
![Cool [8D]](/FSM/CS/emoticons/icon_smile_cool.gif)
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