a friend introduced me to those volcano kettles long ago, actually it was in the wilderness of the remote Zambian bush (I even was on a one week Zambezi rafting tour with the Sobek guys). At that time I used an MSR, Before I had different Optimus, Phoebus, Bleuet etc. Those stoves continue life now in my stove collection.
Frequent Problems with pumps, jets, gaskets etc. made me think to find an alternative way to heat my meals on tour.
Thinking about volcanoe stoves: all I wanted was a smaller version - the 1pt. Kelly now teams up with a (modified of course - with Tatonka titanium pots) Trangia T27 (unfortunately the Caldera Cone wasn´t on the market at that time), both do the job perfectly
Eco-Billy also comes in a smaller size - it wasn´t available at the time I got the Kelly.
Aluminum pots causing Alzheimers desease is IMHO pure rumor - unless someone comes up with a real scientific research.
Copper, as used in the Thermettes, has similiar thermal chartacteristics as aluminum - unfortunately it´s a lot heavier.
Stainless steel (as used in the Eco-Billy) performs not as good as alumium and is heavier.
Dito for titanium