I do not believe the shield will have any effect on the zoom function. The Coyote Light is built with a halo shield and it doesn't keep it from going from wide to narrow. Mainly it keeps the light off the rifle barrel.
As far as the brightness of the SH 66LR, with it on wide zoom that diffuses the light so much that I don't believe it will be a problem. Of course there is the dimmer mode, but with the light on wide view, it doesn't appear bright. It will be a help when they come out with the adjustable dimmer, but even now it should work fine. I've only had mine a few days and haven't hunted it yet.
Preliminary opinion only---It probably is as bright as the Coyote Light when zoomed fully, but covers a smaller area. At 100 yds, you won't need to fully zoom to identify and shoot. Remember you want to get them in the light early as that doesn't effect them as much as just suddenly hitting them with a bright light. Keep the beam dispersed for scanning and zoom just enough to identify and shoot.
The adjustable mount is nice on top of the rifle scope and can get well aligned with the crosshairs. I don't believe I would like it side mounted. There is a little bit of wobble in the head when zooming in or out. It is not bad, but can cause some movement of the alignment with the crosshairs. It is a nice light and a great deal at $185. It won't replace my Coyote Light but will be available to my hunting buddies when they need a light.
Jeremiah, let us know when you have the shields available.
. Super fast shipping to boot. I got the red LED version. Used it the other night and had no trouble seeing/IDing critters out to 300+ yards. Called in 3 coyotes and killed 2. First one was 200 or so yards and could easily see the entire coyote 2nd was around 100 and was very lit up. I just plain ole missed the third not fault of the light. 
