You can try to get a refund, but again I don't condone hurting a small business because of the risk that the customer took. I consider this fraud and won't be part of it.
(The above can be changed if the company advertised falsehoods such as BFL, but so far Terrahash has done nothing wrong (No matter what the "Kooks" will have you think))
Selling the Hardware once Terrahash ships is probably your best bet. People will pay a fairly good amount for HashPower in Hand.
If you are feeling a little brave and risky, you can mine with your hardware for 2-3 Weeks after receiving it and then Sell it for a decent price. As long as No HUGE players like KnC Ship during this timeframe you might come out ahead of just selling it when receiving.
Either way, there are still plenty of options. Hell if KnC misses their deadline this Unit could pay for itself easily. (I don't think KnC will miss that deadline)
That being said a 75% linear monthly difficulty increase isn't going to stay that way past maybe 3-4 months. Then it will level off unless you see some other big players selling $2/GH units. (Could happen!)
Thanks for your feedback Bargraphics. I'm cautiously leaning towards mining for a few weeks and then selling if anyone will buy the TH hardware at that time. It feels a little risky, but gets me closer to my original goal of mining BTC. I don't hope anything bad for KnC, but if they miss their date, I won't be too disappointed. I wish I had bet on both, but did not see it in KnC until it was too late for me.