I recommend sticking with Windows mainly because of the full version of One Note. I have it on my SP2 and all of my notes are available, automatically (through the magic cloud), on my Samsung Note Edge. I have used One Note for taking notes in my graduate engineering classes, in meetings, and for planning things out. I can e-mail them to anyone in my building (we all have One Note on our desktops) and they can open them, otherwise I can export them as PDF files or Word documents and e-mail them. The full version of One Note is truly one of the best note taking programs. It is far more stable and versatile than the note taking apps I have tried on the iPad (Notes Plus and iAnnotate to name a few) and it runs better than the Android and iOS versions while having more features.
At this point, I don't see a reason why anyone would buy a Surface Pro 1 unless they want to use it as a secondary system around the house. Yeah, the processor in it is still a great performer and the SP1 will be upgraded to Windows 10 but, by today's standards, it is thick, heavy, the 16X9 screen isn't as good as the 3X2 displays in the SP3 and Surface 3 for note taking, and the battery life is outright atrocious practically requiring the Power Cover (which adds weight and thickness) just to push the 6 hour mark of browsing in the touch version of IE 11. That doesn't really bode well for something that is supposed to be super portable, like a tablet.
The Surface 3 is a lot more portable, has better battery life without requiring a battery keyboard, you can carry around a battery pack (about the size of a smartphone) if you really wanted to push going all day and night, and the Atom x7 CPU is still fine for everyday tasks along with media consumption (it can playback 4K video content). The Surface 3 is an improvement over the SP1 in every single aspect except raw performance. I think the 0.7 lb decrease in weight, better aspect ratio, larger display, decrease in thickness, and doubling of battery life outweigh having ~30% more performance.