My thumb rides the safety the moment my hand is on the firearm...it's where it rests coming off the beaver tail. I can click it off in the holster if I want to. I used to shoot IDPA twice a week....I haven't since my son was born last July and I can tell you safeties don't slow anyone's presentation down.If you do in fact train to do so, how quickly can you draw your firearm, release the safety, acquire your target and fire two rounds?
The safety on my SR-9....that's a different story. It's a little tiny, difficult to engage pain in the ass. I have a feeling that type of safety is what you're comparing them to. The safeties on my Colts are massive paddles that are impossible to miss. I actually cut mine down and made them smaller on one of them.