If they do this with the router hanging on the chains, a person can inadvertently pull on the router/sled and obscure the results. I did this test as well, at the advice of Jay_Settle. I may have influenced the cutter; hard to tell. As you can see from the irregular hole, installing the router and linkage is no joke. If you read through my posts you can see how carefully I tried to do it the best way possible (using a drill press) and still ended up with a distorted hole. This is another reason why I ordered metalmaslow’s kit; thinking that, being laser cut, some of the critical holes and dimensions are done for you).
This all ties back in to what I was saying yesterday about kit makers doing a bit more to prepare, or even pre-assemble (for a fee), critical components like this and also what gero was saying here: