IR3 air pressure or angels in general

[dcwang3]

Hi, I'm getting into Angels and I'm sort of new to them. I would like to know what the different between a LP and HP gun setup. What exactly is the difference (other than that they operate at different psi settings). What is beneficial for either of them? Suggestions?

I'm looking at like a 2003 IR3 CC Angel, is that a good choice?

Thanks!