I'm not sure I see the difference. Once you've commited your 1 Bitcoin at today's value, you have effectively paid that price, irrespective of when you receive

I'm not sure I see the difference. Once you've commited your 1 Bitcoin at today's value, you have effectively paid that price, irrespective of when you receive the product. If the value of Bitcoin fluctuates between now and the time you receive your product, then you may "lose" or "win", but that's a chance you take, even with the product in hand. In other words, there is still the possibility that your 1 Bitcoin could have allowed you to purchase something more valuable than the product in hand at some point down the road. Seems that the only thing you give up with a preorder is the interest potential or use of the money for some period before receiving the value (i.e. product). But, that would be the case with a preorder irrespective of the currency used.