I've had a small Wix store setup for almost six months now. Not one single sale. The products sell well in our brick and mortar, as well as countless other sites. Sure, our traffic is relatively modest at between 1200 and 2000 uniques per month. Quite a bit are organic, or qualified referrals. Still, not one single sale. I have made two purchases to test the cart system and those went fine. If anyone has any insight, I'd love to hear it.
I've also been playing around with the Ecwid store. Two things I do like much better. It is fully responsive (Wix store is not) and the root page can have sub pages or categories indicated by icons. The Wix store wants to lump everything on the root page, and offers a filter system. This would be fine on sub pages, but I like the way Ecwid does it on the root page better.