PBN uses charge coupled capacitors in the M Series speakers. I have heard a couple of models in the line. Shocking transparency from the mids up. Not what you would call budget designs though.
I keep things simple and use Sonicaps with a Miflex copper bypass (Danny’s recommendation). Long break in time but I can’t imagine better sound for the money.
One thing you have to do if adding batteries to your crossover. Make them easily accessible. Mine are not.