"Quote from Extreme Alpinism "On the other hand, thick warm boots are clunky. There is no right answer, only compromise. After years of supremacy, plastic boots now face competition from a new breed of leather boots. Some leather boots weigh less than plastic models but many dont. Then new leather boots climb better in some situation then their plastic counterpart." -End of quote
Why does he call plastic clunky? Why is the flexible sole of leather better? You know what is to be gained by reducing underfoot insulation? FEEL. This feel give you the really security in the mountains not spikes or crampons."
He calls plastic clunky just by comparison with the then new generation of leather rigid boots. Before The Nepal Top (or maybe other, that's the older I remember), everything was clunky, in fact the plastic boots aren't clunky if you compare them with the previous leather options, like leather TRIPLE boots, those felt like a fallout shelther on each foot. There's no advantage in "feeling" the ice, you need more input than the tactile to know where to place your points, no substitute for that, not even the new vibram sole (the one with wool inserts).
Also there's no flexible sole on the leather/soft Alpinism boots, he is talking about the ankle. And that's the main difference with the plastic boots, you can place the front point easily and faster and with less energy use. You can use semi-rigid boots for front pointing, but those boots have a limit.
Of course, this is applied to alpine climbing, not ascending trekking peaks in Nepal (I think you're talking about that). For a trekking peak you don't need stiff boots, the trekking company uses them (probably scarpa inferno or old style koflachs) because a leather boot has a more critical fit so you need more pairs of several
models. On a trekking peak you just need a semirigid ligthly insulated boot. Even if you are extremely cold resistant, with any boot there's a reduction in blood flow, more if it's stiff (look at the mukluks) that means increased chance of frostbite.
So, as I see it, it's really suicidal, at least you should have "fly wings" or "butterflies" on your very thin sole, just like the old pre-Vittorio soles.
Disclosure: I'm a year round sandal user (ask in Chamonix, I'm sure someone remembers)I keep all my toes in a semioptimal shape and sometimes hike barefoot. Also an ex-alpinist.