I don't believe this is a consistent way of calculating ARPU- it...

I don't believe this is a consistent way of calculating ARPU- it is ONE way, but not the only way. I would imagine ARPU is considerably higher- go back and watch recent interviews to see where Adrian clearly states that they have set and met all their targets. There is no way that targets were set to underperform, so if they have achieved their set targets then I would estimate ARPU to be considerably higher. You have used a static text book model for calculations but if customer growth is up 12.5% (THAT'S A WHOPPING 50% IN A YEAR IF THEY DO THIS FOR THE NEXT 3 QUARTERS!) and merchant payments up 18% , I would estimate ARPU is up considerably ,too. All of these figures have been achieved during what is essentially a testing phase, with the 'go to market' occurring on May 1st. I can't think of another tech company off the top of my head that has produced comparable figures at a similar stage of their development. I expect the market to react favourably tomorrow, and if it doesn't, it will be out of ignorance. Why would anyone sell out just a week from launch proper?