honestly, any carrier will get hot because there is body heat, but the moby seems thicker and is just so much fabric. the regular k'tan does get warm but is less material, so not quite as mummifying. also, the k'tan breeze is half mesh and is cooler.
Re: Baby K'Tan
Baby k'tan makes a mesh one which would be cooler. https://www.babyktan.com/breezewhite.html
The moby and the regular baby k'tan would be equally as hot though, although I have both and I think the moby is a heavier fabric.