As has been stated, the market is experiencing a bit of a bounce right now. This could mean that you are not upside down at all. I am familiar with Madeira Canyon and Anthem. It is very popular and should bring a premium. Frankly, whether you walk away with cash in your pocket depends on how anxious you are to move. If you have time, the market may improve (if it hasn't already) to where you can get what you need. On the other hand, because this market is so heated up and with 57% of all sales last month being cash offers, you may find someone who will be willing to jump the current market value and pay your price, just to avoid having to wait for a short sale to go through.
I would also suspect that since you are living in your home, it is well cared for, unlike many of the current short sales that have tenants in them, or foreclosures that sustained damage during the foreclosure process. Let me give you a no-obligation market analysis and lets see just how much equity you have. Having been in the business for more than 32 years, I have learned that connecting with an agent you trust, who is knowledgeable, and who has your best interests in mind, will net you not only the most money, but also the most satisfying experience.
Call or email me. Let's see if there is a fit.
Best of luck, and thanks for reading.