Sony NEX vs Nikon D5100?

I'm looking to upgrade my camera and have narrowed it down to a D5100, NEX-F3, or NEX-5N. A NEX-6 would be ideal, but I don't want to drop a grand on a casual hobby. The D5100 has everything I want at a price I like, however the size/weight is an issue. Both NEXs have image quality comparable to the D5100, but the F3 lacks a built-in viewfinder and the 5N lacks both a built-in flash and viewfinder.

So basically my question is for people who have gone from an SLR to an NEX; do you find the lack of a built in flash and/or viewfinder restrictive?

Added (1). Are there limitations other than the lack of a viewfinder/flash? I'm not too concerned with lens compatibility since it seems old MF lenses can be readily adapted. Also I don't plan on using an autofocus lens besides the kit 18-55 and probably a prime

Added (2). The lower end NEX models don't have any viewfinder; they are only available as a $2-300 accessory. I'm also not a big fan of EVFs so I probably wouldn't even buy one. I only considered the NEX because image quality is comparable to an SLR, yet it's a fraction of the size, meaning I'd use it more.

Both should be able to provide excellent pictures. The DSLR offers more potential capability and more compatible lenses. The lighter Sony CSC has more limitations, but it is easier to travel with. Of course if you add more accessory lenses even a CSC kit can get cumbersome.

They are two different kinds of cameras. The Nikon is an upper entry level D-SLR. The Sony is a EVIL camera: Electronic Viewfinder Interchangeable Lens…
Here's a clue, pros never use live view. You need a viewfinder you can look through as the LCD screen will often become washed out in outdoor shots. You can't see what you're trying to take a photo of.