Diet and exercise are certainly more effective than CT (although I am interested in how a combination of all three would work - going even stricter on diet, harder/softer on exercise, and adding in CT). This post indicates that ketogenic diets as well as MILD cold stimulate thermogenesis by way of UCP:
Conditioning Research: Mitochondrial Un-coupling (!)
I believe it's the same people that Mark posted about as supporting mild cold (60ish). I realize that they may have given them the kiddie-cold version so as to avoid any hypothermia lawsuits by participants, however I have no doubt that there are some negative effects to extreme cold immersion. Exercise is a hormetic stressor when in the right intensity and frequency. When overdone, it is simply stressful and damages the body. Cold is a hormetic stressor when in the right intensity and frequency. When overdone, it is also stressful - as was pointed out, it spikes adrenaline and thus cortisol. If you're taking a 45min ice bath, that's around the point that Mark says it's too much running. Furthermore, Wim Hof is great and all, but just because he can do it all and appear healthy doesn't mean he is optimally healthy internally. He also doesn't look like Brad Pitt, which I think is the goal for CT-users rather than running ice marathons that almost make you lose your toes (around 6:50):
Extraordinary people - Iceman - YouTube
On the topic of spot-icing killing fat cells rather than shrinking them, that's great and all but it's not unique. It is a myth that fat cells are immortal. Fat cells have life cycles like all other cells in the body - spot-icing kills them, certainly, but so does diet/exercise. If you diet your way to smaller fat cells, and you had an excess amount b/c you were overweight or obese, then eventually your body will "pare" away these excess cells through apoptosis, because caloric restriction would dictate that your body cannot support that many fat cells with fewer calories. Thus, over time, the fat cells will be killed. So while losing the weight, it's important to keep up the good diet/exercise or you can put weight back on quickly, as in the case of yo-yo dieting where stretches of binge eating can rapidly re-fill the fat cells that you so painstakingly emptied before those cells have committed cellular suicide.
So CT works, but so does diet and exercise (and variations to bust plateaus). Extremely cold stuff is in no way necessary to get past a plateau. Mild cold + ketogenic diet may add up to the beneficial effects of very cold CT, whilst saving yourself from the negatives. Just a thought.