Buff,
The 155 Anthem uses a single needle/tip combo so you don't need any other needle or tip sizes such as you mentioned with the Crescendo 175.
These are both siphon-feed airbrushes by the way and they need a bottle or color cup attached to them to paint with.
Some people like them as do I, but for strictly modeling I would go with a gravity-feed such as the Omni 4000. It is also a single needle/tip combo and sprays great from thick to thin lines.
The Omni 4000 with an airhose runs about the same price as the 175 set you mentioned also.
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