Whiteknight, I have the talon set with all three sizes. I can get finer lines with the .25 and I've even done an entire painting with that size. But I generaly use the .38 set up. The reason I don't use the .25 that much is because of the way I clean my airbrush between colors. The .25 takes longer to clean out than the .38. So I'm bound and determined to get fine lines with the .38 setup. Now maybe when I get alot better at painting, I may use the .25 more.
At one time I even considered buying the mojo III needle,nozzle and aircap( .20 size ) for my talon, since the mojo III was made from the Talon so they will work.
But then I thought to myself, if I don't use the .25 much, then whyi would I need the .20. I just may purchase the .20 setup and put it aside for when I get better.
As was said, with experience, you can get fine detail with the larger sizes. It depends on your ability and what your altamate goal is.
Just my 2 cents.