Just some food for thought. I also invest in real estate in North Carolina. It sounds like you are in a good position with cash flow on your properties. If you wanted to take a chance on more shares of AMBS you could always get an equity loan. Granted rates are not as good as they were, but even at 4.5% - 6.5% APR, you could cash out some or all of the equity to invest as you will, and still have the income to pay the note back. Then if AMBS hits like we think it will, you can sell the property to pay back the loan. Your taxes will be much better that way. You pay no taxes on borrowed money.
Been working for me for about 15 years.