benefit of polar star is that it's only 1 moving part in the entire compression system... the electricly fired solenoid.... it's extremely robust and reliable and because it's HPA is not subjected to temperature swings causing fps variation.
Drawback is that you drag a paintball sized tank around with you...
and that it's expensive. your aeg, plus 500-600 for the unit and then 200$ for air regulator rig and then your tank.
The good news is that it's drop in to any v2 aeg so you can just pick up a cheap m4 and P* it. Also the p* retains its value because of the extreme reliability of the mechanism.
Couple guys local to me filled up 1 scuba tank at the beginning of the year and both of them have been using it all year to fill their carry tanks between 2 guns. It's just starting to taper off now and will probably need a charge sometime soon.
I personally don't like the P* for the lack of feedback... if people feel AEGs are too quiet and innadequate the polarstar's bloop bloop bloop when it shoots even less satisfying.
I futz with V2s, V3s and V6s. I could be wrong... but probably, most likely not, as far as I know.