I have/have used two different adjustable stems - both quill stems. The difference between the two stems was was both reach and length - yep, enough of a difference to "require" switching to the second adjustable stem after two months of riding/adjustments. Once I found the "correct" position using drop bars, I just kept it installed - until I decided to mount some clip-on aerobars. Then I switched back to the first adjustable stem because it worked better in terms of getting the elbow pads AND the hands-on-the-horizontal-part-of-the-drop-bars position comfortable.
While I have made note of/determined what the corect dimensions for a non-adjustable quill stem for me should be, the additional weight of the adjustable stem is negligible AND I haven't had any "loosened bolt" problems thus far. I'll probably keep it as is for the foreseeable future.