I picked up the Garmin S20 2nd hand from the bay for £100. Does the same stats as the S40 from what I can tell and doesn't appear to have missed any shots so far. Doesn't measure putts unless you have the CT10 sensors. Stats on the Garmin app aren't as good as I've seen elsewhere though (ShotScope, Arccos or even MyRoundPro app). Didn't want to pay as much for SS, had Arccos with my Cobra clubs but wasn't impressed with it missing shots or the subscription fee, and MyRoundPro only works on Apple Watch.