I love the Kelly Kettle. Mine has a 16 oz reservoir, and the kettle itself weighs about (stock weight) is 20 ounces. If you hack off the chain, cork, and handle, you end up at around 18 ounces.
But you have to add back some wire for a handle and a piece of wire to replace the chain. I've used piano wire (total added back is 0.2 oz). These two pieces are useful for pouring water out of the kettle, and of course, toting it around.
The main disadvantage of the KK is the volume. It's big and takes a lot of room in the pack. But heck, most of us have room to spare in our packs, so...not a huge deal.
The KK will be featured in BPL's upcoming Wood Stove Review Summary which will appear later this summer, alongside a whole bunch of other wood stove designs, all of them commercially available.
Of the entire lot that is being tested, the KK far and away uses (1) the least amount of fuel, (2) burns wood most efficiently (ie to ash), and (3) burns the most different types of wood efficiently. I think it's the best designed wood cooker available for really crappy, wet, fuel sources. 3-5 minute boil times per pint are not at all unreasonable with the KK.
If it wasn't so darned big, and heavy, I'd consider taking it on my Arctic trek. However, I'm in need of something more compact and that will work with a conventional pot that will hold more prodigious quantities of food, which of course, the KK can't do - it's strictly a water boiler.
So instead, I'll be taking a 4 oz double wall, stainless wood gas stove that nests nicely into a 0.9L Snowpeak ti pot that is nearly as efficient as the KK but a whole lot lighter and smaller. More on that one soon enough, but here it is in action: