The conductivity of the material definitely makes a difference to how hot something feels in our hands. If you touch a metal object (like a handrail or flagpole) on a hot day it will feel hotter than something like a piece of wood (like a tree) next to it; even though the wood and metal are the same exact temperature. The metal can conduct heat into your hand faster vs. wood. For example aluminum has a thermal conductivity rating of 205 while pine has a thermal rating of 0.15. If you touch the same materials on a cold day, the metal will feel cooler than the wood since the transfer of thermal energy is going the other way (hand -> material) and heat only moves in one direction (hot to cold). Personally I didn't find the IQ to get anywhere near "to hot to hold" for me, even after several back-to-back sessions. I understand that people have different heat tolerances, and I'm sure that's the reason why some people don't like how hot it can get.