There's a kid around these parts who's been on the USA Cycling development squad, raced in Belgium etc. I think he's unattached now but still races at the Pro/Cat 1 level all the time. He uses an adjustable to get the bars lower; his saddle to bar drop is ridonkulous. But, the savings he gets from reduced aerodynamic drag far, far outweigh the additional grams of an adjustable stem. If adjustables are solid enough for riders like that then you should be fine with one while you figure out the ideal angle.