I have the Moza Air. Look for B&H's occasional $400 sale. It has the best specs and features in that price range.
I'm a product photographer that shoots some videos, I'm guessing you're a photographer as well, since no one buys this camera over a GH5 for it's video spec.
Set up is easy, it handles the weight quite well, the size is another issue. The D850 with my Sigma Art 35 or Nikon 14-24 the camera has to be so far back that if you pitch a large amount, the camera would hit the motor. Yaw is fine and my main use, in addition to overall stabilization.
I couldn't use the 14-24 with the Manfrotto quick release adapter I wanted to add, I forget if it was weight or clearance. If I shoot more videos, I'll pick up some lighter 1.8 primes.
Battery life is great.
You can't focus with the button like Canon and other brands can, damn you Nikon!
The screen will be partially obstructed, but you can make it work. The batteries for my field monitor just came in, so I'll try the 2 hand grip with monitor, though I'll need the $120 remote for any movements. The Ronin-S is designed better since the motors don't obstruct the display.
There are setup videos on YouTube and search for the firmware upgrade video, since it isn't exactly obvious.
I bought the Glidecam HD2000 after seeing Devin Super Tramp rave about it. I used it back in the day with my D800, but never got comfortable enough with it to use on a real job. The Moza Air is soooo much easier, just skip the Glidecam unless you need something with no power for a 2 week backcountry trip.