While I can't comment about the ease of building the X-Omni's, since I bought mine, I can say that the X-Omni's work well as front L/R speakers. I used them in that role for a while until I upgraded to the GR Research O-3's, which are a definite step up from the Omni's. But for the price of the Omni's, they are very difficult to beat. They through a huge and effortless soundstage, and I love watching sports with Danny's omni speakers. I've also heard the X-Statiks, and while the Omni's may be a shade less than what they are, it's pretty close. Also, my guess would be that the X-Voce is a pretty good fit with the Omni's as mains.
But please do remember that the Omni's like space. You can't stick them up against the walls and expect them to sound good. During my experimentation with them, they needed to be at least 2 feet off of the walls to sound good, and 3 feet is preferable. The X-Statiks are the same, BTW.