And on higher levels, you'll just be trading techs anyway. I always make my first leader an army, and use every leader after that to rush small wonders. It came in really helpful in my first SID game, when I had 5 extra MGL to rush small wonders, and I was behind in tech but still in the information age. I caught up in tech, used the 5 MGL's on the biggest space ship parts, built the rest at core cities, and viola! Victory!