Like mentioned above, I used small sections of spa flex near my return pump in an effort to minimize pump vibration and noise. I'd say I have 3ft section going from sump to return pump, then a 5 foot section going from pump toward the display. Where the spa flex ends on the return line it joins rigid pvc and goes to the tank from there.
I found it worked really well at quieting the return and reducing vibrations. I'm a fan. But I don't know that I'd necessarily do the entire thing in spa flex, would be costly and I don't know that the benefit outweighs the effort.