My K3SO has paid for itself and it is only about 6 months old. I now have a K4SO as well and it has already provided about 1/3 of its cost back in savings. BTW, These are items I would have purchased anyway but got a discount through a KSO.

This is why I probably won't get SO models in the future unless I'm getting rid of my current SO model(s). There is little need to have multiple SO models other than the discount up front. In my experience only a single SO has been allowed to be used multiple times, and that was a recent 50% off on selected covers. They only allowed that because the SO was for specific covers for the applicable model, so my K3 got the SO on K3 covers only and my K4 got the SO on K4 covers only. Unfortunately some people noted Amazon messed up and sent K4SO customers the K3 offer instead.