Well, as everyone says, it depends.

I took a tour in the american west and some people used triples but many of the riders from Colorado used doubles. I was just as fast on the climbs as the people with the doubles, I was just running a much higher cadence. Of course, out there the steepest grades usually max out at 7% but Teton Pass is a sustained 10%.

So depending on your fitness and your riding style, you could go either way. One way to test is go out and find a local hill that is at least 7% and climb it with your proposed gearing. During the climb, ask yourself if you could do this for say 8 miles without a let up especially when you are a little beaten up.

Also, in all my time of cycling, I have heard many people talking about wishing they had a lower gear on the climbs on many hills but I never recall anyone complaining about having gearing that is too low.