I race most of the time and always cleat the main. As Howard said, I have the angle adjusted so that I have to raise my hand quite a bit to cleat it. Then as the gust hits I uncleat (the slightest tug does it) - I do not ease the main unless I have to, just uncleat - then cleat again when the danger is past. If you do not have your main in tight, you will not point to well. The same with the jib - my crew would always have it cleated and only release it if a very strong gust hits, or to re-adjust it if the wind strength changes.
I always have the mainsheet in my hand, except when using the traveller downwind. I pitchpole once or twice a year, but cannot remember when I last capsized on a beat.