To add my bit..whether it be the activators or an Alembic bass,the sound is unique and to everyone in the club it is the best sound.
The good points are clarity, an almost infinite number of tonal options, no loss of signal with long cables, no loss of tone when the volume is turned down..and much more.
The bad points...the pu's will emphasise any sloppy playing technique so they educate you to play better as well.
Oh yes..they are expensive
To add, that website ibpesq linked..are they direct copies of Alembics..surely they are infringing copyright there even though there is no logo on the headstock!