I have a Voile Split Decision and love it.
Kelly, I would look for a Voile board. They have been making them for a while and you can find them used. The construction quality is great and the Viole binding system is good. It takes a little tweaking to get it set up right but once you do you will not have any problems with it.
I never rode on the Burton system but played with it at the local shop a number of times and it looked horrible. I'd be wary of the Atomic board system as well. Reviews of it's binding system are not good.
With splitboarding, one thing that you have to be comfortable with is a quick change from climb to ride. The Voile system does that well. It's simple and there are not many ways it can clog up with snow. Clogs of snow tend to be easily cleared by the act of disassembling and assembling it. It's well designed.
If your hardboots fit well, and it sounds like they do, I would think you'd want to go with a plate binding for the split like the Voile Mountain Plate or Bomber Splitboard Binding.