Thanks for your input.
I agree that many of the so-called detailing airbrushes are very sexy-looking, and I've been so tempted to buy one so many times. In another thread, I think I mentioned I'd almost buy a Sotar at the $56 sale price just to have in on my bench and impress myself. Though I'd never use it.
And I'd be a a little more vocal than you on having no need for a .15mm airbrush. I can't see how one would have any use at all based on the materials we spray in our hobby.
I read a quote from Ken of Badger fame just the other day, paraphrasing it went like this; tip size has more to do with the viscosity of what we are spraying and very little to do with ability to spray a fine line. I'm pretty sure Don Wheeler has mentioned the same thing in more than one instance on his website.
I've yet to fine anything I can do with my H&S Infinity with the .3mm tip that I can't do with my Iwata HP-CS with a .5mm tip, for example.
My rambling two cents, anyway.