I like the idea of a longer game tests (instead of a furmark run). Kudos!!!
The witcher 3 will do nicely, if you also list the CPU/GPU clocks and CPU/GPU temperatures.
Take this notebook for example. CPU (91W) is cooled properly and maintains it's max Turbo at 4.4GHz consistently during Heaven but the GPU is dropping quite a lot and according to GPU-z it's overheating.
That explains why it is not in the 1800MHz range but in the 1600Mhz range. 90Celsius is too much for any Nvidia GPU and Heaven is not the biggest challenge for a GTX 1080 anymore.
If you compare all notebooks and besides listing the sustained fps in the Withcher 3 but also list the CPU/GPU clocks and temperatures, so people can compare them by themselves they can make an educated decision.
Maybe some GTX 1080 notebooks (due to throttling) might be outperformed by GTX 1070 notebooks, which gives you a better bang for your buck.