I weigh about 175 lbs and have an Ozone Little Devil 3 meter as my only kite. I had the kite for nearly a year before getting an MBS Jeep Renegade board. This seemed a cheaper way to get into kite locomotion than going out and getting a buggy.

I find that when the wind blows pretty hard I have to work the kite near the edges of the window to keep the board from going so fast that it gets squirrelly. This speed seems to be about as fast as I could run. It can get pretty scarey when it catches a puff and the speed picks up suddenly. But if the wind is less, I have trouble getting the board moving at all, particularly if trying to go cross-wind. There seems to be a very narrow range of wind conditions that give me a comfortable ride without working really hard.

Now here's my question: Would a larger kite give me more power at lower wind speeds? Would it be more or less vulnerable to gusts?

You will find it mentioned several times on this forum that large kites in low wind offers safer, stable power for kite traction. As you have noticed, small kites in high wind fly fast and develop sudden bursts of power. They fly erratically in gusts easily flipping over and diving to the ground.

There are situations where a 3 meter kite is the right choice (so hang onto it). I fly a 3m on long lines when the wind is high but stable. The long lines (100ft+) cause the kite to fly and react more slowly, and smooth conditions allow you to find the sweet spot in the sky where the power is dependable.

But less wind with larger kites offer the best buggy/skate/ATB conditions. Because they are larger and develop more power, you can leave them parked near the edge of the wind window where they can better deal with gusts while enjoying enough power to roll.

Hang on to your 3m kite, but look into buying a 5m+ and a good harness, then try skating in less wind. BTW: "cross-wind" is the direction you should be going most of the time.