So now that I've gotten a little experience with this device, I wanted to share some thoughts.
First, a bit about my setup. I have a sling studio hub, a battery (which isn't necessary unless you're in a location with no power), the USB adapter (necessary for attaching an external hard drive), 4 iphones and a 10.5" iPad Pro. I got some OctoMounts off of amazon so that I could easily mount the iphones to tripods and/or mic stands, use the Ipad or a Macbook to run the control app and I was off to the races.
My first time using this was in the mountains back in August when we were shooting footage for two music videos for two pieces off of Sandi Siegel's latest album. I set up four camera's and set them to record to the sling's external hard drive so that I could use my DJI Osmo to get some handheld shots, or for the shoot on the lake, fly my DJI Phantom 4 drone. Everything seemed to work pretty well during the shoots, but when I got back home to check out the footage I had corrupted footage from several of the camera's on the first day (two different locations).
Day 2, the lake location, was a real train-wreck. Even though I double and triple-checked that the system was set up to record all of the inputs, it only recorded the program material, which was set to a single camera for the whole shoot (as I was running the drone). This was really disappointing for all the effort that went into set up, and I may not have enough camera angles to do a whole video I may need to plan and do a second shoot so there is more material for the video. There was other drama for that shoot anyway, like not being able to get our actors together in the morning when the light was best and only being able to shoot at 3-4pm in the afternoon (when the light was not so good), and then the high amount of wind kept pushing the kayaker's and paddle-boarder's out of the center of the shots I had set up. Good times!
The big learning for me is that maybe cheap iphones streaming over wifi to a sling box is not the best way to go for a serious shoot when so much work has gone into planning and setup. A set of DLSR's with various lenses is now on my wish list. It might be a little more hassle (and more expensive, obviously) but knowing that you have the recording on an SD card on the camera will give me a lot more confidence that I will capture the necessary material.
I have used it one more time since then, this time to record and broadcast a live performance. What I learned this time around is that if you set the broadcast to stream at 720p, all of the footage also gets recorded in 720p. I wanted to record at 1080p so that when creating stand-alone videos in post I could create a 720p project but scale up some of the video to be able to zoom in on some of the artists. Not an option for me this time, since all the footage was already at 720p. Next time, I'll stream at 1080p to make sure I get 1080p footage and pray that the uplink on the local broadband can handle the extra demand. I used an iPad to control the live production instead of my Macbook (which was busy recording the live multi-track), and the iOS app actually seems a little more solid than the OSX app. I had no issues with corrupted video this time, which might be something I did differently in the recording setup, or it might be that software/firmware update I installed the day before the live show.
And the last learning on this is that it appears you can only broadcast to a single destination, even though you can configure both youtube or facebook live stream destinations simultaneously. I think that streaming live to facebook will serve most needs for the time being, but if I wanted to do multiple sites I'll need to get a live streaming distribution service where I could send the live feed to that and then have that service push the feed out to facebook, youtube, vimeo, what have you.
All in all, it's a nice live broadcasting setup, possibly the best you can get for under $2,000 (including 4xHD cameras). I have a feeling that I'll be using it a lot for live recording and streaming work, but I may ditch it for the next highly-produced music video shoot (after I shell out a few grand for some decent HD-video DLSR's).