I have a NEX7 and an SX40 and I live in the southwest USA.
Both are good cameras. I use both of them regularly.
Choosing between a NEX5N and a SX50, I would go for the NEX5N. The only advantage of the SX50 over the NEX is the long zoom. And very few of my keepers are taken with the long zoom of the SX40.
If you are into bird pictures, the long zoom of a SX40/50 is nice. But the southwest has drabbly colored birds and not that many of them. Road runners are very cool, but incredibly fast, moving all the time. A real challenge to get a good photo of. I have cruised throught a number of commerical websites trying to find a good road runner picture and have not found any that reflect the beauty of the subtle blue around the eyes or how they fluff up in cold weather. None of them reflect the character of these living dinosaurs, but I am digressing.
When I crop pictures taken with the NEX7, I get roughly the same resolution as the zoomed in pictures taken with the SX40.
As far as speed, the SX40 is a slow. I have lots of good pictures of my kids, from it, but also lots of empty frames too.
But I do recommend checking out the image quality of the kit lens if possible before buying the NEX5N. I hear most are good, but mine is not. On mine it is easy to see if you just take a picture of a newspaper. I get a fuzzy patch. But with my Tamron 18200 lens I usually use with my NEX7, the image is clean all over. So it is my kit lens and not the camera body.