The height we get is limited to the venue. This particular venue is outside, but there is a large tree that limits how high we can crank the truss. In this case, the bottom of the cabs are about 8 feet off of the dance floor area. We believe that provides several advantages.
1) We are able to angle the speakers downward to more evenly cover the dance floor and the immediate area about 50 feet from the stage. This is a "backyard" area at a restaurant that is in a neighborhood, so they are very concerned about sound levels beyond the fence. As such, we must limit the bass from the subs as well. Conventional stacks would provide less even coverage and more "spillover" past the fence line. If you walk in an arc about 30 feet from our stage, side-to-side, you will note very even coverage throughout the listening area, with little/no noticeable holes or high frequency combing. With 140 degree coverage from each side, we are also able to get a pretty wide stereo sound field, which we take advantage of in the mix.
2) This venue is quite wide beyond the stage, so conventional stacks of speakers would block audience sight lines and make the stage less open.
3) We would have to build a stack about 11 feet high to accomplish the same speaker height in this venue. In addition to losing the previous 2 benefits, I would argue this is less safe (subject to tip-over) than what we are doing.
As far as cable-on-truss concerns, normal practice might be to provide some type of soft interface between the cable and the truss, but at less than 50lbs hanging on each cable, I see no issue with cable fray or truss wear. We have been using this rig for about a year with no visible wear whatsoever.
We have used this front truss rig in several of the quite small venues we play in from time to time, and have had very good results. We are able to make these gigs look much bigger and more impressive versus the typical "lights on a tree" approach. People are amazed when they stick their heads in the bar, and they come in to check it out, which is exactly what we want. Once we get them in, we can usually keep them with the quality work we do.
It would be nice to play in larger, better paying venues, but we are weekend warriors and prefer to stay very local. But that doesn't mean we can't have a little fun with the staging and setup. Also, I personally like to innovate and experiment a little with the latest gadgets (such as the LED lighting, wireless laptop FOH control, etc.), and love it when people wonder how the hell we are doing some of the stuff we do. It's part of the entertainment value for me in this out-of-control hobby of mine.
Again, I appreciate everyone's concerns, but I am convinced this is safe. In fact, far safer than many things I have seen other bands/clubs do. Also, I am not advocating anyone else try to copy what I have done. This thread was originally about LED lighting, and I did not intend for my little truss/fly system to get us off track.