I ordered and installed with an EMG 85.
To be honest, I have no need for a built in booster.
My idea was to go for the 18v mod with the 85. So I needed another battery clip. If you check the price of an EMG wire kit, its more expensive than the PA2. I only needed the battery clip and with some extra research probably I could find a cheaper solution rather than buy a PA2... but I thought it will be fun to have this little boost in my guitar (plus I dont have cover an extra hole with ducktape).
I play alone and I not gigging, so I not using it much, but in live situation it will be useful for sure.
Don't turn it max, it will be a bad experience. Around half way the ideal.
Its a good to have little stuff. If you play solos, surely go for it!