I have had to replace both high pressure hoses on my watermaker, and I used standard hydraulic hose. I am pretty sure that between the RO membranes, and the carbon filters I use on the freshwater supply something else will kill me first... Pretty sure.
There is also high pressure rated hose that is all plastic, no braided SS cover. Works fine, just be really careful to protect it from chafe anywhere it touches anything.
For anyone who doesn't know:
According to every hydraulic guy I ever talked to, other than age, and stress cracking of the stainless fittings from salt, the biggest cause of failure of these fitting is over-tightening. For many of these fittings the actual torque spec range is quite narrow. For 3/8" hose it is 17ft-lb min, 19 ft-lbs max. That's a very tough spec range to meet by feel!
If you have a torque wrench that will fit, use it. If not, do what I did, and practice with the torque wrench on a bolt several times until you know what the spec torque feels like before you crank these down with your standard wrenches.