My 2 cents:
I use the Iwata Eclipse for just about all General Purpose work (all acrylics). The airbrush it self is top notch: great quality, easy dissasembly for maintenance and easy to use. The only downfall is it doesn't spray hairline patterns, at least with the factory set-up (or maybe it's me who is the problem!).
I have to switch to a second AB for fine detail, but if I could have only one, the general purpose Eclipse is a real workhorse. The HP is a step above the Eclipse, but as you said, more expensive. I'd make your choice based on what your airbrushing needs/preferences are.