I have only ever flown without a helmet when for some reason one has not been available.
I spent the whole time feeling vulnerable and uncomfortable without one, even at OATs up to the high 30's Centigrade and high humidity.
It's probably just what you are used to.
Oops sorry disregard. Just reread the original post - I'm not a CPL. Why don't ATPLs count?
[This message has been edited by ShyTorque (edited 20 November 2000).]