I've had an Iwata HP-BC2 for well over 20 years using it for everything imaginable. This past year is the first time I'm using it on models and I couldn't be happier. I use Tamiya acrylics, thin with iso (usually right in the cup). After I flush 50-50 mix iso/water pulling the action back and forth aiming into the side of a plastic bowl. I drop the color cup in bowl pull the needle out, wipe it , put it back in, blast some straight water through. Back the needle away from the seat, close up the sleeve and into the box. I may be doing something wrong, I have never owned a different brush, but it works for me...
By the way, it's the original needle, hose and compressor all from way back. I just added a reg and larger moisture trap recently. Love it.