Could you please confirm whether the HP PS Pro B9180 driver supports 16 bits per channel or not.
This could arguably make a difference for some types of image; in any case, some people may be expecting this of all new 'Pro' printers from now on.
The ink set doesn't require high bit workflow on the 9180. That said in Maximum Detail print mode quality there are indeed high bit (16) for some screening and colour functions. That is precisely why you see a difference in image quality with a loupe in this IQ mode, but doubtful you see this at normal viewing distance for many images.
For Canon with the 12 ink printers high bit images going to 12 bit screens and multi pass is a definite advantage. Yet the controls on the channels are at this point rgb driven so yet to be seen which rip makers will venture into the bigger world of colour.