One thing I haven't seen discussed is the thermal properties of this expected Ti-6Al-4V alloy.

According to these specs, the alloys thermal conductivity is 6.7 W/m-K: https://asm.matweb.com/search/SpecificMaterial.asp?bassnum=m...

Whereas 6063-T6 aluminium has a thermal conductivity of 200 W/m-K: https://asm.matweb.com/search/SpecificMaterial.asp?bassnum=M...

Even if the alloy in the iPhone is a bit more of an exotic blend, won't it still impact the cooling ability of the phone quite significantly?