If you have a system that you are going to add to or just update some components, your existing speakers for example, the passive speakers are your best bet.  Unless you are looking to really upgrade to the next level. I am working with a church right now that has a passive speaker system and are upgrading to a line array.

If they go ahead with the new line array system (they are active) some of the components of their existing system will be sold (excess amps and crossovers etc). They have a 6 speaker Turbo Sound 2 way system (main cluster), the subs are a dual 15" and single 18" cabs on each side of the platform, all powered by QSC amplifiers. They have a 80' x 80' sanctuary with a balcony in back (see pic).

We are proposing an ISP Technologies Active Line Array system consisting of either 6 HDL4210 boxes (12° vertical) and 2 XMAX212 active dual 12" horn loaded subs, or 2 Reference Line 4215 boxes and 2 XMAX212 Subs. We are conducting a listening demo during the week before Thanksgiving. This system will greatly improve the music quality of their system. All the other components of their system will stay. Here is a picture of the demo consisting of 3 x HDL4210s and 1 x XMAX212.