my apologies on the 1370 & 1466, I was thinking of another thread.
The older models I really only used the pi power being at least 2 amps.
On some of the newer models the only problem I have found is the dumps are incomplete.
To over-come that, I would power on the unit, then press & continue holding the power button immediately, then read or write
At which point a clean dump, would need to repeat for a write as well.