My feeling is, if the end result is not different, and I have both a safe and risky method of accomplishing it, it's obvious that I should choose the safe way.
Unless it's a school assignment to see how well I can mitigate necessary risks...
Also consider how convoluted your calling is, compared with:
Serial.print(pascalsToMillibars (barometer.readPressure()) );
that would result from using a static string.