Oh boy. Changing our business model was one of the worst days of my life. I recently relived that day when I saw the ZenDesk thing unfold. Luckily we had grandfathered all our customers when we did the big switch. The problem was that our old system was setup so that Shopify was very cheap for people who weren't successful and became quickly expensive for people who actually sold a lot of product. Everyone who expected to setup a 1M revenue store ( e.g. everyone ) picked up a calculator and realized that.
Once we changed to more of a subscription model for our pricing we ended up getting a lot more customers who build successful businesses. Even though in reality our product became somewhat more expensive overall.