Originally Posted by billtzk
If you are an all-grain brewer, a hydrometer is equally helpful. Either a hydrometer or a refractometer is essential. You need a way to measure gravity, while they are used differently, neither does the job better than the other.
Except with a refractometer you can take a small drop and place to measure your gravity almost immediately. With a hydrometer, you must take a much larger sample and cool it to about room temp before you can make the measurement. The refractometer is much quicker and easier. However you are correct that the hydrometer is sufficient.