Richard, I had a Fernandes Gravity 4-string that I did the same upgrade on, from the no-names that came installed OEM.
I prefer EMG's to Barts. I find several advantages:
The tone is right there without a lot of digging.
Since the preamp is in the shell of the pickup, you can forget about having to shield the guitar's innards, and internally grounded so you don't have to ground off to the bridge, a REAL plus if you've ever been hit by a mic. And these days they're using plug-in connectors, so it's almost a solder-free job (Input jack). Adding their BTC (3 holes/pots) or their BTS Circuit (4 holes / pots) is plug and play, and both feature a dip switch assembly on one of the pots to change the resonant peak (4 choices)
They aren't as present as a Activator PJ set, but they are very smooth, and there doesn't seem to be a big difference in output between the P and the J.
They work fine on 9v. They work even better on 18v, but don't know which battery box you have.
Joey