I recently helped a friend set up their 15A (and yes, I fell in love with it also). My big regret is that I didn't spend any time testing Dolphin on it.
Intel "U" processors are usually not the best to use with Dolphin, as they don't pack a big enough punch. We recommend that you get a full powered laptop with an i7-4700QM (preferably with a GPU that has a dedicated heat-sink, aka a gaming laptop) or a desktop.
However, to answer your question as to the comparison between the two tablets, the 15A should perform better the the Razer Edge. This is because
1) Haswell CPUs are faster in Dolphin and in general (including this case)
2) The 735M is better than the 640M
Someone else can correct me here, but I think if you follow the laptop performance guide and use Throttlestop, you can keep it in the Turbo Boost state when playing Dolphin
https://forums.dolphin-emu.org/Thread-unofficial-laptop-performance-guide
Intel "U" processors are usually not the best to use with Dolphin, as they don't pack a big enough punch. We recommend that you get a full powered laptop with an i7-4700QM (preferably with a GPU that has a dedicated heat-sink, aka a gaming laptop) or a desktop.
However, to answer your question as to the comparison between the two tablets, the 15A should perform better the the Razer Edge. This is because
1) Haswell CPUs are faster in Dolphin and in general (including this case)
2) The 735M is better than the 640M
Someone else can correct me here, but I think if you follow the laptop performance guide and use Throttlestop, you can keep it in the Turbo Boost state when playing Dolphin
https://forums.dolphin-emu.org/Thread-unofficial-laptop-performance-guide