Pylon mounted motor will obviously cool much more easily than enclosed motor cooled through a small hole. Each concept has it's trade offs.
UH

Pylon mounting is the way to go. The FES self-launchers are VERY tricky to launch on a grass field because the prop tip is just a few inches off the ground. I have watched a friend blow up his prop on a grass field with just small bumps in it.
I like the new Polish GP series. The electric motor extends and retracts in just 4 seconds! Too bad there is a 2 year wait. The batteries are adequete now and will get better. There is a huge worldwide effort now to improve them.