Neat though things like the GSI Halulite are, I have to agree with others, that they're not the most compact item for minimalist camping. I've got a similar small aluminium kettle, and unlike a small pan, it's hard to pack stuff inside it, because the opening isn't as large (compared to the body size) as with a pan. I've got small pans with lids, so they'll boil as fast as a kettle, they just don't pour quite as easily.
The folding kettles looks interesting, and would match my folding cup, bowl, and plate, but I would be worried about using them on wood burning stoves, with the risk of the flames being outside the metal base, and damaging the plastic/silicone.
An interesting argument I've seen in favour of the ones in which the upper body is entirely silicone, is that since silicone is a good insulator, they'll loose less heat when exposed to the wind, so the water will boil faster, and use less fuel.
