CNC Depot used to be known as Blurry Customs, who didn't have the best reputation. They produced several different ATC spindles over the years, but they've never been too popular here, most likely due to the cost.
I've heard that their new S30 spindle is a much better spindle than their previous offerings.
There are very few if any members here using ATC spindles, as far as I know, as the cost is usually prohibitive for hobbyists, which most of us are.
An open loop machine will work fine with an ATC spindle.