I actually ended up going the other way. Started with an rMini but exchanged it for an Air after about a week. I had owned an original mini and absolutely loved it. I did find myself zooming in on content quite a bit. However, the device was SO much lighter and comfortable to hold than my iPad 3 that I didn't care. I figured the zooming issue was due to the low res display and would be fixed by a retina version. So, the first day my local Apple store had stock, I reserved one for pickup. The display was amazing! But, I still found myself having to zoom in a lot. Even though small text was now sharp, the mini's smaller display made text too small for me to read comfortably (maybe I'm getting old?). So I tried an Air for a few days and was hooked. For its size, the Air is actually less dense than the rMini and I finally felt it was a full size iPad I could hold one handed for long periods of time. Couple that with the larger display and better color reproduction and I had my winner.
Both are fantastic devices and you can't go wrong with either one. Enjoy your new rMini!
When I bought my wife the first Mini I had the 3rd gen (retina). I loved the size of the Mini, but the screen bothered me coming from a retina screen. I always said that if Apple put of the Mini with retina, I would get that one for my next iPad.
The day the Air came out, I went and tried it out in the store. I loved how much thinner and lighter it was and bought one that weekend.
I just switched to the rMini two weeks ago for a few reasons:
1. When I took my Air out of the house I usually kept it in a backpack, the rMini seems easier to carry on it's own.
2. I will be done with school soon, so I don't have much need for the larger screen.
3. I wanted to mount the rMini in my car, the Air would have been two big.
As you said, both are great devices, each with their own purpose. I have been happy with both.