Having the brightness too high can throw off your perception of whites. When I first got my Dell 2005FPW (minimum brightness of 200cd/m2) I eye-balled some corrections to test the effects of monitor luminance and found I was constantly setting images about 1/2-stop darker than optimal.
That being said, factory specs of luminance and contrast are nearly worthless. (there is no set standard for measuring contrast and contrast changes with luminance. So that number is only useful when comparing displays designed in the same year and from the same company) What is really important is wether the display can reach optimal luminance of 120cd/m2 or at minimum 140cd/m2. Since companies don't publish that number, the only way to find out is to ask the company (and hope for an actual response), trial-by-error or to ask someone that has it already.
If you don't have a calibrator, it won't matter how bright the display is as you are shooting in the dark anyway. Pick up a calibrator and try to calibrate the display. At that point it will tell you if the monitor can be dimmed enough or not.