Definitely worth using if you have the room and the need. I like to cross my tweeters fairly low and that's one of the reasons the Piccolos can go so low. If you are crossing your tweeters at 5k, it's probably not worth the required room.
Being the noob that I am, not sure where I will be doings crossover points at. I was thinking of flexibility. I am pretty sure I can make enough room in my doors for a small chamber. Also considering LPG's since the reviews seem pretty good on them. I'm just trying to soak up info for the best plan. To be honest, the only thing I have dead set is using an Alpine 9887(once I decide where I will buy it).