Well, my suggestion was with respect to folks who wanted a "low cost minimum GSE setup" for motors in the "D through G" (i.e., model rocket) range: my intent is to examine whether the traditional solenoid setup is inherently necessary in order to safely operate hybrids in this size range, or if there are ways to do without it. (I.e., I'm not trying to start a safety flamewar, or to propose avoiding necessary safety precautions, but to examine potential alternatives.)
It looks like the pressure ratings of the best available small bore nylon hose (DOT rated air brake tubing) are in the 1000-1200 psi range (for diameters ranging from 1/8" to 5/16")... copper "refrigeration" tubing, 1/4" OD x .030" wall, is rated at 1400 psi. I'd say it's a "wash" with respect to pressure rating; either should be adequate. Restraining the "away" end is prudent in any case, especially with a "remote tank" fill: even if the tank supply is successfully valved off, there's going to be some venting of the hose contents between the motor and the valve.
-dave w