I would go with rigid pipe to replace rigid pipe.. However before I did that I would price both rigid and flexible... Here is my logic....
Rigid pipe is often put in out of the way places where it's not easily inspected, This pipe generally lasts a long, long, long time (you should last so long) less there is an "incident" such as you had.. Flexible hoses, can go bad, and often do, thus they are better suited to locations easily inspected.
As for the hose.. That line is a LOW PRESSURE line (regulator to appliance) carries about 1/2 PSI.. Any RV store has 10' lengths of HIGH PRESSURE propane hose, (Good fr like 1,000 PSI give or take a couple hundred PSI) such hoses are used with the Extend-a-flow or extend-a-stay type adapters on motor homes and trailers.
Any propane supplier (Wholesaler) will have the hoses, But I'd really give consideration to the fact that line runs where it can not be easily inspected, and go with the copper tubing.
Home is where I park it!