Hello Pierre:
The first thing to notice is the regular wind turbines are available now, in production, whereas the kite-reeling systems are perpetually “coming soon”. That should tell us one thing: They can’t quite even get kite-reeling systems ready for general use, no matter how long time goes on. We’re at 15 years now. Still pretty much nothing working on a regular basis. There must be real reasons, with all the talent and effort behind it.
I’m thinking the problems start with reliable launch and landing, extending to undue wear in the tether reeling system, possibly with gearing wear, maybe generator overheating, problems getting the software tuned right, and maybe kite wear in general, since I know hang gliders and paragliders are only good for so many hundred hours before needing replacement.
As far as the extra weight, I think it speaks to the excess mechanical complication involved, as well as possibly the lack of any reason to need the ground station to be lightweight, since it is not on a tower, and indeed maybe an advantage of it being heavy, so it is not dragged away by the wind, and can be used as-is, without attachment to the ground (no anchors?). The shipping container alone weighs 5000 lbs., which is two-and-a-half tons.
As far as the Hummer and Chinese turbines in general, it is a roll-of-the-dice, and you are definitely taking your chances. They do not have a good reputation for reliability. In fact, if you Google “hummer wind turbine problem”, you will find a lot of warnings about them:
hummer wind turbine problem - Google Search
Some of the discussions degenerate into accusations that the people posting work for competing Chinese turbine companies, talking up their own products or talking down the competitor’s products.
This illustrates how “the wind is brutal” and even just copying what is known to work well is difficult. You’d probably be better off buying a used Vestas from the 1980’s, and rebuilding it.
The thing about wind energy that escapes most would-be innovators is any machinery likes to work in a sweet spot where no component is overly-stressed, where forces balance, and do not reverse a lot, but rather stay more constant.
Think of buying a new car and immediately driving it off-road at high speed on a regular basis. It will quickly start falling apart. Drive the same car at reasonable speeds on smooth roads and it will last many years before having a problem. Same with any machinery. If you want it to last, it has to be designed and built to last, and operated conservatively. 