Usman,
I would be considered a satisfied user.
I purchased a Whisper 3000 used from a man in New Mexico. He lived in the middle of a ring of mountains, and the machine appeared to have had little wind exposure.
I have the unit on an 80 foot tilt-over tower, and it has been in active use for 3 years. It was offline last summer for 2 months after a nearby lightning strike damaged the controller. A new controller was installed in mid-August of 2007 which tracks the kWh produced, and it is reading approximately 5,800 kWh since that time. However, we live in a high wind area. I live in sight of a USDA wind research station that told me that our wind speed is 14.3mph at 30 feet, and my tower is much taller.
I have taken the unit down every 6 months to service it, and, each time, I have found loose bolts on the unit and often bolts missing or sheared off which attach the turbine to the tower. Presently, the nose cone was blown off, and I am waiting for a still day to lower the tower and replace it. I would consider 6 months to be an appropriate time frame for evaluation of the turbine, so your concept of a crane is not very feasible.
In light winds, it makes a soft, pleasant whispering sound, but, in high winds when it furls, it sounds like a helicopter. We live on 12.5 acres, so this is no problem, but I would hesitate to have this unit up in a close residential setting.
I am planning on installing a Proven 6kW which I have already purchased. This machine appears to need much less maintenance. It weighs 1000lb. Many people refer to these machines as "heavy metal". I have been pleased so far with my used Whisper 3000, but, if you are in a high wind area and must use a tower which will not tilt, I would recommend a "heavy metal" machine.
John