Hey Dave,
Order #000154 here. Would have been great if you could have just said, "I don't know when I am going to be able to ship" instead of, "Will ship before Christmas" and then stop answering emails.
And then don't respond to the Paypal refund request.
And then deny the Paypal refund request.
Delays happen, I understand. You need to learn to communicate honestly with your customers a little bit better. I want my unit eventually (I am patient; I can wait), and reassurance that you're not going to just take the money and run. That is preferable to having it sooner, and not knowing.
A good example is these guys on kickstarter:
http://www.kickstarter.com/projects/...er-pocket-acce
http://www.kickstarter.com/projects/...ket-acce/posts
I got SO MANY emails from these guys over every tiny product update. But, when their release date slipped, I had no worries whatsoever; these guys seemed really legit due to the incredible level of transparency.
Please consider a bit of this kind of transparency, and perhaps you'll keep some of your customers.