Some initial feedback.
Question: How can you hold steady an 8x monocular that only weighs 4 oz.? Do you use two hands?
I do use both hands when using the monovid. 1 to hold the monovid, and 1 to focus it.
Now, hand vibration will vary from person to person, and ambient conditions. The best way to hold it for me, is to palm it. Meaning, I place my hand around it, as if I am grasping the handle of a hammer. My hand (medium size) is behind the focus ring, which is located about 16mm behind the front edge of the instrument, sans the close-up attachment. The eye lens is therefore centered in a circle comprised of my thumb and the finger next to it.
I can hold it in that manner as steady as a small binocular to mid size binocular.
That said, i do not think i could hold it steady for as long as i could do a two-hand hold of a bino, if the holding arm i am using to hold it, is not "braced", i.e. against a tree, knee if sitting, car door, etc. But so far, that has not been the case. Just sayin'
Question: Getting "on" the bird?
No. I am not as fast getting on the moving target with the monovid, as with a compact or small binocular. The grip i describe above is part of the reason. A finger hold is for me as fast as a bino, but then I sacrifice the stability of the view.
Initial impressions.
As far as build quality, well, its a Leica product. Enough said.
I am initially going to give my impressions after a little "test" this a.m.
Sun up, early a.m. outside, 1 deg. F. The 3 of the 5 crows in my local family group sitting on branches in a tree, about 100 feet away. Blue sky behind them. I am in my car, window rolled down. Car stopped.
Comparing to my current car bino, Papilio 8.5x21. Obviously the two are in two different leagues as far as optical quality. But, for me, it is the appropriate comparison instrument.
I use field optics for more than birds. Both the monovid (with the close up lense attachment) and the Papilio have a strong close focus feature.
so,
1. Optically, like i inferred above, the monovid is the clear

winner. No contest. It is a very hi res, contrast, flat view. For a 20mm aperture, it is hard for me to imagine better. Also, i could not notice CA.
BUT, if you really are sensitive to a view sometimes described as tunnel-like- or looking through a tube, and that is an uber alles issue for you, you may want to be sure to try in person before ordering. Given the size constraints on the intended design, that may be unavoidable.
2. Comfort of the view. For me, the Papillio had a much more comfortable view. That makes since being the all other things being equal, using two eyes for a person with two functioning eyes, will almost always be more comfortable.
Of course the virtue of the Monovid is its size. As i type this, it is in the breast pocket of my shirt, with the neck lanyard (optional, extra purchase :C ) around my neck. Probably more on that later....