[font=trebuchet ms]One way to look at it is to consider the preamp as a boost pedal built into the guitar. What I don't like about active systems is that the pickups are usually very high output to begin with, so they don't get as much of their tone from the guitar itself as a lower-output passive pickup does.
The good news is that a crappy guitar with active pickups will sound pretty much the same as a really good guitar with active pickups. :)
The bad news is that a really good guitar with active pickups will sound pretty much the same as a crappy guitar with active pickups. :p
So if you have a crappy guitar and you wanna wail with the metaloids, active pickups will get you there. If you have a good guitar, you're much better off installing pickups that will let people hear that you have a good guitar.[/font]