Firstly i know what ur all gonna say but in trials brakes are only ever used on or off so there would be no heat build up from prolonged braking to boil the water wich would in turn lead to air in the system
I am now experimenting with my shimano disc wich is minrel oil like maguras so in thery should work better like maggys do initial feel is improved and i have what seems to be a much more responsive lever i will let people know how it goes wether or not it fails or works a treat
All in all its just an experiment i have a few hydro discs around so y not