just curious, does that Surface Book top configuration include the 2nd GPU?
Whats the GPU option on the rMBP?
Cause for $400 more for a Laptop with the "clipboard" detachable touchscreen functionality AND the discrete GPU changes things as you will get a lot better performance from the Surface Book than the rMBP
Well, its a little complicated. For the non-dGPU models, the the Surface Book carries a $200 premium. The dGPU wouldn't even be much faster if the 13" rMBP was using Skylake with the Iris 550.
Also, Apple's and Microsoft's SSDs aren't created equal. MS's SSDs only get 300mb/s write, IIRC.
To finish, the high end models are actually even more expensive than a 15" rMBP. At $2700, the only real benefit is the detachable screen. Compare it to Razer blade 14, and the value is even worse.
With that said, its a cool machine and would totally buy one. The pen and detachable screen are really going to have to make a difference to your workflow on to make it worth it on the high end, especially when the rMBPs and Razer Blade 14 get skylake.