I can't comment on the 3rd gen because the 4 is my first iPad. However, after heavy basic use the last 24 hours (iCloud restore, firmware/software update, Twitter, Facebook, streaming videos and music, email, iMessage and of course MR, it doesn't appear to have changed one bit externally in heat emission. I'm using it with a Smart Cover. I will also add the battery is freaking amazing. Any other questions about the 4 I'll be glad to try to answer.