UPDATE!! 2013-08-06
My first CD has matured, and I have paid out all my mining profits. Not as much as I'd hoped, but now I have some liquidity. What will be my next move?
Buy more AMUs? Buy alternative hardware? Another CD? Cash out to fiat? Invest in shares or derivatives?
Give me a suggestion with a rationale and I will consider it!!
This is probably way too late but what the heck ...

Since you seem more on the hobbyist level (like me), you may want to consider doing something different than what you've already done, to increase your learning.
You have some mining hardware, and you're mining BTC, so you've "done that".
You made the loan, and had it work out well.
So maybe the securities, or mine another SHA256coin other than Bitcoin, or possibly even start building a non-SHA256 mining setup?
Curious to hear what you do ..
-wot_gup