They are mildly popular. Component sets have three main advantages over most coaxial speakers.
1. Seperate tweeter allows you to do more complex installs
2. Crossovers are generally superior.
3. Build quality of the drivers.
When you say full range, I assume that you are talking about a coaxial rather than just a single driver that plays all the freq. SoundQ SVT has some Xtant coax drivers in his IASCA winning vehicle. One advantage in his system is the simplicity of acheiving a "point source" where all of the sound is coming from one location.
If you wanted to check out some full range units with no tweeter, check out the Jordan JX92s, it is one of the best full range units on the market and will play comfortably from 60-20000hz.
