I used the CEM70 for the first time few days ago, and before i used the EQ6.
When you run the PPA it suggest a movement to WEST of 30degrees and it move 2times and take 3pictures to calculate the polar deviation.
If you use the iPolar, you dont use the movement of 30+30degrees, but probably you have at the end a movement of few degree.
Greatest is the movement more precise should be the calculate of the polar deviation. 
This is just my opinion

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