I have 8 of them powered with four of the lowly Crown XLS5000's, one sub per side of an amp. We have used them for over 400 shows over the past 3 year of owning them and NEVER had a failure.
As far as the sound, very musical with decent low end. However, we did do an outdoor street party here in Fort wayne with Coolio with over 1500+ people cramming the street and they blurred vision at 30-40' back for 2 hours straight. Once again no failures. Plenty of "throw" to cover nearly 200'.
There have been times I have wanted to get into the mid 30hz/low 40hz but for the little amount of power these take to light them up and the volume they produce, it is tough to justify. I really like them and plan on getting 4 more.