For those who have or are considering engine monitors, options are available for hydraulic pressure monitoring. I have such a transducer measuring hydraulic pressure at the block where the pressure switch is located, and displayed on my MVP 50 engine monitor. Set point is 1250 psi, and yellow alert is at 1400 psi. I have seen 1500 psi rarely due to temperature rise and heat soaking of the airframe after a long cold soak at altitude, but a blip of flaps or (in my case) hydraulic speed brakes immediately reduces pressure into the control range. Now hydraulic pressure is part of my pre-takeoff and pre-landing checks when I scan the monitor to make sure everything is showing green.
Fred Moreno