Well, my P75-C1 finally came yesterday. Powered on OK and looked good, so sent the delivery guys off. Then I started the setup, and it started doing its firmware update.
At 20% of the install, it errored out, displaying on the screen that there was an error updating the firmware. I immediately called Vizio, and they had me unplug it and hold power button and such. No matter what we did after, we couldn't get the screen to power on. The power LED would indicate that it was turning on, and you could turn it off once, but the second time you'd try turning it on the power LED would come on and stay on for good until you powered it off. No screen activity whatsoever - completely dark off. We tried a USB update, but no luck on that either. Still bricked. Ended up opening a service call for someone to come repair it hopefully by late next week.
I thought about it a bit more, and checked and noticed I was able to ping the TV, so it was responsive in some way. Hmm. I switched the firmware update to a USB stick that had a little flashing light to show activity, and noticed that I could get it to read the USB stick on the first power on, but then it seemed to hang. In a last ditch desperation, I unplugged everything including the USB stick. Then I plugged it back in without the USB stick in, and turned it off and on once, and then stuck the USB stick in. This time, the USB stick flashed for a fair bit longer, but still nothing on the screen. Waited 10 minutes, no luck. Then said '**** it' and went to play Ghost Recon.
About 30 minutes into that, I glanced left and noticed there was a glow coming from the TV. Went over and checked, and it was powered on and bitching that the tablet remote wasn't paired. Restarted that process, and everything was good. I still can't believe it. I ended up calling Vizio back and gave them the specific steps that were required (mainly not having the USB stick in during the initial plug-in since based on the light flashing, I think that made a significant difference) and the approximate time that I think it took to update itself.
What a fiasco.
But I have a working TV, and it looks great! Significantly better at everything than the Sharp LC-70UQ17U that it's replacing. I tried Rocket League on my PS4 and it was actually responsive! The display lag on the Sharp seemed to be >100ms no matter what game modes were being used. Going from that to 20ms or whatever made the game playable.
In general the TV has a lot less display lag. I had to go into my receiver and get rid of 125ms of audio delay that I had built into every mode. Now the lip-sync modes work on everything, and even with my UDP-203 connected directly to the TV for display (and the 2nd hdmi to the receiver for audio) everything lined up perfectly after removing all the delays I'd built in. The Spears and Munsil A/V sync test was right on the green, maybe a couple ms off but I honestly can't tell when it's below 5-10ms or so.
Either way, I'm annoyed with the setup problems, and annoyed that I had to go buy some M8-12 bolts for the wall mount, but happy with the TV so far in the end. You'd think a $3700 TV could come with the proper mounting bolts