I am a D800 owner and recently I purchased the SmallHD DP6 1280x800 hiRes monitor.
I 've read that when I record to card, HDMI outputs limits at 720p. (note: I don't want to record the HDMI output, just feed the monitor)
Well, this is my case:
Video on the monitor looks great when in live view mode, but when I press record the video cuts out as the camera is now sending a smaller video format and the monitor takes a few seconds to adjust to the new stream.

I tried both 720p and AUTO in setup/HDMI/output resolution.

When I set AUTO then:
I am in the menus: DP6 receives 1080i signal
I am in Lv: DP6 receives 1080i signal
I start recording on card: DP6 turns to blue and then receives 720p signal

When I set 720p then:
I am in the menus: DP6 receives 720p signal
I am in Lv: DP6 receives 1080i signal (!)
I start recording on card: DP6 turns to blue and then receives 720p signal

My other settings:
D800 fw: A:1.01 B:1.02
DP6 fw: 2.1.1
D800 movie settings: 1920x1080/25fps/hQ
D800 setup/HDMI/advanced: Output Range=Limited, output display size=100%, Lv OSD display=OFF

I just connected D800 to my samsung FullHD 40'' TV
I set 720p in D800setup/HDMI/output resolution.

Same behaviour, when in Lv it displays 1080i, when I press record, signal stops for 1 sec and then turns into 720p

Just tested my D4 AND my D3200
both same behaviour, when I press record, image disappears and comes again in 720p

I shall make another statement.

No matter what I choose in HDMI settings (I tested many combinations) I cannot get the monitor to show video continuously from Lv to Recording.
I tested 3 cameras, 3 cables and 2 HDTVs !

Please someone check your Nikon at home and share with me the result

anybody could test at home ?
D800-->HDMI-->TV when recording starts, TV goes off for 2 secs

Yup, this was observed in the NanoFlash testing with the D800. The only way to remedy this is to use an external recorder with the D800 and not use any cards in the camera itself, then connecting the DP6 to the external recorder.

This is due to the D800's reading of EDID data from the monitor. If the monitor is sending out the wrong EDID info, the camera chooses the next best resolution. The 720p limit with cards inserted however is artificially created in the firmware and can't be bypassed as long as a card is in the camera. They don't want you to simultaneously record to an external recorder at full quality and to the card in the camera itself. Thus, creating headaches for people that just want to monitor and not record off the HDMI with a card in the camera.

Thanks for info.
I just discovered I can't record even in 720/50p. The HDMI signal turns to 576i !!!
The only recordable signal that can simultaneously be outputting to HDMI is 720/25p...

An Atmos Ninja might remedy these woes since you won't have a card in the camera and your recordings will be of higher quality. You could still pass through to your DP6 and monitor as well.

Well I almost bought ninja2
when I realised it can't (as well as odyssey7Q) record 1080/50p
signal coming out of my other camcorders, sony A7 and sony NEX-EA50

The O7Q has the capability to record 1080p50, but you have to convert HDMI to 3G-SDI to record 1080p50. It's internal HDMI in is limited to 1080p30. You can still hook your devices that don't need 1080p50 directly into the Odyssey.

You could use a Blackmagic Battery-based HDMI -> 3G-SDI to record 1080p50 from your cameras: Blackmagic Design HDMI to SDI Battery Converter CONVBATT/HS B&H

This is an interesting thread. Did you ever get a solution that worked for viewing higher res output on your monitor?

I have a wedding coming up in June where I'm going to want to get some shallow DOF shots during the Pre-Ceremony and Reception. I'm kind of holding out to see if Nikon does a D400/7200 before then, but it's not looking good.

So, I'm probably going to plunge and get a D800 since it allows real time exposure control while recording.

Something that concerns me is focus, and so I've been looking at a lot of external 5"-7" monitors that incorporate focus peaking, but I'm seeing reviews say that on DSLRs, the actual on-screen image is like 3" and such.

What has your experience been with just trying to accurately focus the D800 using the back LCD?