you can fry eggs on those suckers. try unscrewing one with your bare hands!
Even with a tiny bit of airflow it's already cool enough to hold it for a longer period and unscrew it. (the 100W)
Without it gets too hot to touch comfortably.
Just tested it with my own 13W (1521 lumen 2700K) bulbs.
20W Osram Parathoms aren't bulbs you want to touch.
Maybe with an airflow of at least 1 m/s, but they're pretty hot.
They're good bulbs though, little hotter than I really wanted but sockets can take a higher temp than the nerves in my hand.
They're also rather cheap, about the price per watt as a Gavita DE.
And I think by now they should be more efficient too, 117lm/w for the Philips bulb, that's including diffuser/PSU losses. Without diffuser it should be 130 lm/w at the least.