One quote from some friends of mine is that if you have low gears on your bike, it doesn't mean you're a sissy; it means you know where the good hills are.
My own input is that if you're choosing between a triple and a double, you should pay attention to the difference in q-factor. It doesn't matter at all to some people, but it does matter to others. And some prefer it wide, some prefer it narrow. Personally I'm much more comfortable with a narrow q, so even my touring bike has a compact double and a gigantic cassette instead of a triple. If you're used to a MTB, you're comfortable on it, and your knees are happy, that might be a good reason to stick with a crank that has similar dimensions. To me, that would be a bigger concern than the difference in shifting performance or weight between a double and a triple.