I just made this decision last week, Andrew. I've owned an RT, almost continuously since its release, and it is still my favorite Surface. The RT is absolutely the best buy in computing (extending Mike's point), and it does 80-90% of what I need and want of a portable computing device. If my now-8.1-RT went down, I'd get a replacement, even though I now have a Pro 2.
Now, for your question, Andrew, and my choice: I decided several months ago that I wanted to replace a nice i5 Toshiba Porteg?, because I was finding it too inconvenient compared to a Surface, and that a fine machine was mostly just being wasted. When the Surface 3 came out, I was tempted, but I was unsure about the bigger screen, the new lighter tone, and the new keyboard design. In early September, I found a great deal on an 8/256 Pro 2 and decided to try it out, confident that I could return it within Microsoft's wonderful, generous 45-day window (in the US, at least), and upgrade to a Surface 3. Last week -at about 30 days- I decided to keep the Surface 2. I decided that the above screen/tone/keyboard distinctions were still clear Pro 2 preferences for me, even if the 3 is lighter and thinner -amazing factors that did almost persuade me because I so admire these kinds of achievements. I also decided I'd rather spend the cash-difference on photography toys -one of my 2 other only weaknesses :wink:.
Note that there is a second-generation Pro 2 that comes with the same CPU the 3 has: look for a 4300U, 1.90/2.50 Ghz specification on the PC info screen. It's a great choice-set; we're fortunate: weigh your own preferences/priorities and enjoy your new Surface.