Upload & Sell: On
I had to sell my 5dII recently and have downsized to nex-5n, thinking it could be a reasonably cheap good quality camera. I've done some videos on both and here are my thoughts:
On my 5D II I mostly shot handheld with zeiss 28/2 and 50/2, anything longer introduced considerable shake, unles shot on a tripod. Both lenses proved very practical from the standpoint of weight, manual focus operation and relative ease to keep camera stable. Maintaining focus at large apertures was not very assuring since the LCD is not very high res, but surprisingly I nailed the focus most of the times.
Now, NEX-5N, I tried it with the kit 18-55 lens and also Zeiss 35/2 ZM lens. The IS in the kit lens was extremely helpful throughout the entire 17-55 range. I no longer had to focus on trying to keep the lens steady, anybody, including my wife could easily keep it steady. Focus peaking on the LCD or EVF is superb, it makes it so much easier to maintain manual focus. When doing video outside during the day, you can just go by the peaking to judge focus even if you can't recognize details due to glare - this is major plus compared to 5D II. I did have an external viewfinder for the 5D II LCD, but because the LCD is of such a low resolution it wasn't optimal, it mostly helped with the outdoor glare and also helped stabilize the body a bit.
Autofocus on the nex-5n worked reasonably well, but I must say I much prefer MF. The camera does face recognition and sometimes focus may jump from one face to another. Because these cameras are capable of such a narrow DOF, I find it more reliable to use MF. Now, if I'm doing a video of my son running on an empty field, AF would work. But if I do his soccer game, the camera doesn't know which player is my son. I assume you could try to use a center focus point and keep it on the object, but I rarely compose shots or video with subject in the middle. Especially in video the composition is important as you don't have the room to crop in post processing as you would with a static shot.
The biggest dissapointment with the NEX-5n was video quality. I don't know if it was because of the slow kit lens, or non-optimal performance with the Zeiss 35/2 ZM, but the video was significantly behind the 5D II quality. I wasn't very happy about it. In the end I returned the NEX back to Amazon. My opinion might have been different if Sony had some high quality NEX lenses availalbe. The kit lens just wasn't doing it for me.
To be honest, if image stabilization and AF is important to you, the SONY a77 is probably the best bet now. It has some of the nice video features that NEX has, such as EVF, focus peaking, video AF, 1080/60p, plus access to high quality Alpha lenses. The NEX system is not mature yet as a system.
I personally have for now ended up with 60D (there were some great deals during black friday), which is not as good as 5D II IQ wise, but it's reasonably close. I'm looking forward to next year for 5DIII - I hope it will have higher res tiltable LCD, focusing peaking and less moire in video, or SONY FF with EVF (basically a77 with FF sensor)