I might be able to help you with the Xaar print head. This is not rocket science. Can you send me the data sheets?
The HP head will perform well at a variety of pulse width times with flexability on the voltage height of the pulse. It's more important to give it the correct "energy" pulse than anything else. And the time between pulses allows the dynamics of the fluidics to get back to a normalized state.
Best of luck,
Mike A.
malden1960@gmail.com