absolutely true.

I have heard that campagnolo is even smaller, though I have never ridden it.

Personally I have rival and I love it. I have ridden all the Shimano groupsets from Sora to Dura ace, and all the shifters from tiagra up are pretty much the same shape. Not as good as SRAM in my opinion when actually in the hoods, but somehow it is easier to put your hands "behind" the hoods- holding the rear of the hood and the side of the handlebar.