This is a tough one. Given that the G is a wound string, the wire core on it is usually the thinnest of all the strings. This means that the G is the most likely to break. Also, changing tunings is harder on the strings than just leaving them in one tuning. However, folks do change tunings and it shouldn't always cause a string to break.
If these are the regular D'Addario lights (.012-.054), the should be up to the task. They're good strings. You might, however, try another brand, just to see. Martins or John Pearse are good strings, too.
-Raf
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-Raf
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