CPU: Intel i7 4790 (Stock)
GPU: R9 295x2 (Stock)
RAM: Kingston HyperX Beast 16GB 2133CL12
Motherboard: MSI Z87M-Gaming
Storage: Samsung 840 EVO (OS)
Storage: WD 1TB 7200RPM (Game)
Display: Dell P2415Q 4K
VSync ON @ 60 FPS
Overall performance was fantastic. There was no multi-GPU profile, though I can't imagine a situation where a system would need it. Visually the game is quite simplistic, but there's a fair amount of physics going on in the background. It may look simple, but the impact from the visuals is just stunning overall. Its raw polygons, but incredibly visceral. Despite my best efforts I was never able to break the game, so in its present state I'm unaware of any particular bugs. Once or twice I might cry foul, but it turns out there was always I guy behind me I wasn't aware of. Unity games done right are just plain solid.
For reference, you can see how your GPU will perform in comparison to ours with this set of charts.
NOTE: Precisely 50% GPU usage means only one GPU was put under load on the 295x2. This may indicate a lack of multi-GPU support.