My company, Cashier Live (http://www.cashierlive.com), is in the same space as Erply and some others. We haven't ran into Square competitively at all, as Square is getting their business traction from mobile businesses & small quick serve restaurants/coffee shops/bakeries etc.. Cashier Live (and Erply, from what I can tell) is targeted towards retailers with inventory on the shelves, something Square isn't good for.