Showing my Tri-axle Trailer some TLC . . .

[bruceb58]

That's why I used quotes. The concern expressed was around excessive hydraulic compliance (softness) in the brake system, thus resulting in greater master cylinder stroke to achieve a given pressure, be it via brake pedal stroke on a car or surge brake actuator stroke on a trailer. Sounds like that all rubber lines are fine on a trailer. Mine has mostly metal lines, so I don't have that experience.

There is no benefit having hard lines in a trailer system...there will be no softness bad enough to change the braking effectiveness with all the "slop" that already exists in the braking system. The max pressure is still applied and that is after various mechanical linkages add their delay to the system. Even if you have an EOH system like I have on my boat and travel trailer. The 1/2 second it takes to pressurize the brake system fully by the EOH pump(even with disc brakes) is far more than any resilience in the brake lines because they are rubber.