Chiming in here after using my impact 4k now for a handful of night hunts in cold weather as well as night use at the range.
First off I love it over the radius. No question it's better than the radius in every way except maybe range button location/power button.
Ranging capability is nuts. 3600+yds in daylight. Zeroing using NV is all I've done but it takes minutes to do at the most. Didn't even use the daylight laser last time. Just double tap it to scan, check through the scope using a pvs30 for where the "/" slanted laser is impacting in the optic and coalign it to something a long ways away. Couldn't be easier.
Ballistics are within .1 mils of my AB app on the phone out beyond 1200yds and that could simply be due to the onboard atmospherics vs my kestrel and AB on the phone.
Now for the annoyances....
Location of the power button without using the remote is an absolute nightmare if using the unit farther up on an ar15 rail. Especially when gloved. The amount of times I missed an opportunity on a coyote trying to find the power button and ranging it were unreal. The smallest most non-discernable location for the most important button on the unit? Stupid. I don't want to need a damn remote and never even considered one with the radius. That button was easy.
The screen brightness on the dimmest setting is nuts. If you've been out on a moonless night and used this unit you might as well have powered up an x300 turbo in your face. Coyotes will undoubtedly notice you glowing like the sun when you try to get a range. Not cool. I have solved this issue by adding a thing piece of neutral density filter. A drop of water on the screen, a cut to fit piece of filter and a q-tip to press it on and squeeze the water out like doing window tint. So far it's held up to 11 degrees Fahrenheit and I did two 3% layers. I will be swapping to a single 6% or 9% piece in the near future. So far. That problem is solved fairly easily.
The moon glinting off the huge glass front end is real. Setting the caller and walking back the other night was pretty obvious something looked off due to the lens. Mkm ARD on order.
The battery life at low temps (sub 30 degrees) is poor. I chewed through 3 cr123a in a single night (same 11 degree night) not necessarily because the unit was dead yet. But because it ate 75% of the power and I didn't want to risk a dead unit on a stand. Warm the batteries back up and they're about 50% alive yet but kind of useless for the winter hunting use... 4$ a piece. Ouch.
The cold also made the screen go blank yet back-lit for about 1-2 seconds before displaying a readout. Scan mode basically kept the unit non-display and back-lit but no read out due to the continual pulse of the ranger and obviously this nuked battery life quick.
As a whole I enjoy the unit and it has helped me take shots faster and more confident on steel in the dark than the radius ever could. The readout for ballistics is near instantaneous when it's warmer out. The ballistics are plenty close enough to anything I could ever expect from anything other than my phone and AB. I will be adding a small rubber bump stop to the ranging/power button to see if that helps with identifying the button with gloves. Hopefully it doesn't tear off right away.
More to come