Problem is, Otzi, that not everyone is able to use this harness as well as the pictured testimonials. Some used it for a couple hours per night. Um, the suggested limit is 30-40 minutes. No diabetics. Well there goes half the adult population! Nobody with asthma, nor skin reactions to cold. OK. Nobody with cardio or heart problems. There goes half the other half.
Now a lot of these might just be CYR (Cover Your Rear) recommendations to avoid messy litigation and insurance problems. Probably are, AAMOF. Nevertheless, there are enough kernels of truth to provide flashing caution lights to wholesale adoption of cold thermogenesis.
So how long have you been using it, and how could you possibly improve on your past examples of cold hardiness, or even be able to tell?