Should be know risk. The liquid propane is the same pressure, it's the outlet of the regulator that changes. Essentially you'll have less molecules/burner tip so the flame won't be as powerful, you will still have hydrocarbons there though so it will burn. As long as the flame lights and stays lit, you should have no issue. You can test your high power burner now by switching the regulators out with the other one and see how the flame looks. I'm sure you'll be fine.
The only safety issue is if the flame doesn't stay lit and then you have hydrocarbon pouring through creating a vapor cloud.