My Rating: 

We recently upgraded our sound system at the church where I play on Sundays. We decided to go with a system that let's you control your own monitor mix. So everyone can finally hear themselves.
The technology is pretty cool. It uses CAT5 cable to send encoded 8 channel audio back to each mixer. So the cabling is simple. The delay is less than 1.5ms which is not noticeable at all. It also has a limiter with a variable threshold, but I found the attack to be a bit too fast. So in more aggressive settings it distorted a bit.
It has a line out which could be used to drive self-powered speakers, but the primary use is with earbuds. I would probably prefer near field monitors (i.e. small self-powered speakers) to earbuds because it feels like you're in a recording studio instead of on-stage. It's kinda weird.
Bottom line: this system is great for being able to hear yourself, but it feels a bit antiseptic and performing with earbuds is a new experience for me.