I used to work as an iOS engineer at LEGO. They're a phenomenally professional company who consistently pushes innovation in-house. I'd be shocked to see them react negatively to this.
I used to tinker with the older version of Mindstorms with Java and .NET, can confirm they were all about helping us as much as possible when setting up the intro to robotics course at the local comm. college.
Love the idea and effort behind this, but concerned as to how Lego is going to react. The fact that they don't appear to hack the original software, but use a dual-booting arrangement is probably good news.
I heard a rumor that the Ev3dev Kernel guys got 4-color mode for the display of the original ev3 brick to work. Not even the lego guys managed to do that.
It's hard to argue that it's cheap but I believe the value is there. The quality of their products tends to be second to none and the freedom to combine and it also seems hack is phenomenal.
You can replace the actual ev3 brick with a raspberryPi based BrickPi or PiStorms. Then a motor or sensor is about 30 bucks and you might have some lego technic already lying around.