I'm one of those small-framed people, and I'm mostly a seated climber. My climbing style is mostly to maintain a steady power output with a fairly constant level of effort, and staying seated works best for this. Standing works great for bursts of acceleration, but it's really not the fastest way to get up a hill. I will climb out of the saddle to relieve pressure or accelerate, but it's hard for me to climb at a steady pace out of the saddle rather than just accelerating. It's a waste of energy. Now that I've started racing, I would like to develop a good jump on the slopes (I am a climber, after all), so I might find myself out of the saddle more often. We'll see, since I haven't developed a racing 'style' just yet. For recreational riding, though, it really makes sense to save energy and stay seated as much as possible.