I have owned the HF-G10, multiple GH2's, the Sony 5n, the Nex-7 and have "graduated" to the Sony Alpha SLT-A57.
I loved the 5n, but hated the lens choices. For video, I wanted a nice fixed aperture lens as I hate having the exposure change if I zoom in a little bit, which I do filming kids riding scooters. So I bought the LA-EA2 adapter to use with the Alpha lenses (bought the Sony 16-50 F/2.8) and really was blown away by phase detect autofocus and how fast the focus was.
Bought the Nex-7 after the prices calmed down a bit. I was unimpressed by the low light performance due to the pixel density of 24MP; it just wasn't as good in low light as the 5n and at least with the 5n the video was mostly usable @ ISO3200. Not so with the NEX-7. Also with the 7 I kept hitting the movie record button; it's in a very silly place right where your thumb is. Like Ken says, the OVF on the 7 was fantastic.
However, the NEX-7 will overheat in video mode after a few minutes just like the NEX-5n. It's so random and frustrating; but I have witnesses it shut off after 3-4 minutes and last the full 29:50. Bought genuine Sony HG DUO memory and still no change. I took the 5n to Florida for a family vacation in March and in the 93 degree weather the 5n would shut down in 2 minutes every time without an overheat indicator.
Also, with the Alpha lenses and the LA-EA2 adapter the camera became bulky, which defeated the "stealth-mode" raison d'etre of the 5n/7.
Lastly, the smaller NEX bodies do not have in camera stabilization.
So here's where I was. Liked the Alpha lenses, liked the video detail, hated the overheating and the lack of stabilization. Looked at the Sony Alpha cameras and the SLT-A57 came out. Reasonable price tag ($699 body), does the AVCHD ver 2.0 1080p60/1080p24 video, in-body stabilization, takes great pics and works with all Minolta/Alpha mount lenses.
I have no looked back and very glad to be rid of the NEX-7 and 5n. I recorded 2 hours in 30 minute chunks with the A57 and don't have overheating problems.
Shot this a couple of days ago with the A57; the video scene does change at around the 1:00 mark so it's not just a static boring shot.http://vimeo.com/42047647