If concerned about low light performance, you can't expect any decent performance from an optic in the price range of the Vortex Diamondback. Just not gonna happen.
If you can afford it, you need to step up to at least the Vortex Viper HD or Nikon Monarch X type bino. The sub $300 binos just aren't going to give you what you're looking for. In that price range, low light performance cannot even be expected much at all.
Then you have to consider how long you think you'll be looking through the glass. Hours on end throughout the day? Days on end with many hours during long hunting trips? Or just quick glances here and there while hunting from a tree stand? The low end optics are only ok for brief glassing sessions because the amount of distortion and color fringing created by the poor glass will cause great strain to your eyes if used too long. Most of the higher end optics with modern HD and APO lenses allow for long glassing sessions that won't leave you with a blinding headache at the end of the day. The Vortex Diamondback is no such optic.
If you plan on using your binoculars on a regular basis, I highly recommend spending a good bit more money on something like the Vortex Razor HD's, Zeiss Conquest HD's, Meopta Meostar HDs, or perhaps even Swarovski glass if you can afford it. You won't regret it.