I destroyed 2x TRP hy/rd calipers on a single descent trying to stay slow behind vehicle traffic.
Stick with mechanical unless you have the cash to upgrade to oversized 4-pistion downhill calipers like shimano saint.
Mechanical Spyre or Bengal calipers are dual action calipers. Mechanical is hard on the hands though.
Magura e-bike floating roters are nice also.
I have had Saint calipers for ~2 years. have not had to bleed the system yet. Have changed pads 3x now. ended up with metallic in the rear and organic front.
I use the rear as a drag brake on steep downhills without any issues. Magura e-bike floating rotors are nice also.
Have been running tubeless for 3 years on a 650b co-mo tandem. 47mm WTB Byway on Velocity Cliffhanger. 32 spokes on "road / lite gravel" wheels and 36 spokes on 55mm knobby everything else wheels.
Road - We run 45 to 55 psi, depending on route
Trail - 35 to 40 psi
We changed over because of potholes and pinch flats. Have not had one yet, though a few instances if we were running tubes I am sure we would have flatted.
Both wheels have been rock solid and I would run 32 again f/r.