I’ve only used the ShotKam once so far and it was very easy to fit and zero in. They don't sell the Mini anymore, so I was worried about the added weight, but it is not really noticeable.
The battery easily lasted for a couple rounds of clays and a review of some shots. Reviewing the shots did show me some of the bad habits I’ve developed. I shoot gun down and my mount is not as good and smooth as it should be but I'm working on it.
I was very happy to get all this useful feedback from my first use. I can see why people don't want to train without it.