RE: Motocalc Recommendation
I punched up the numbers. Looks good to me. 2.5 Amps is no problem for the 280 motor. 5.8 ounces of thrust in a 14oz plane is a little light, but you should be able to manage a reasonable climb. The runtime is phenomenal!
You can get a better thrust-to-weight ratio by using an 8-cell pack of 300 or 370 mAh NiMH cells. They're 2/3 AAA, but are closer to half the size and weight of the 720's. The cells I'm talking about are like the Gold Peak GP37AAAM cells sold at dynamoelectrics.com. I bet you can get a custom pack made at cheapbatterypacks.com.