Motor loading aside, I would keep away from 3 and 4 blade props, as they are inefficient. I like softer more flexible props. On the old glow motors we could stick them into the ground at full speed, and bend them back and keep flying. Some indoor leckies I had were bad, like my Sukoi. I just put a similar more flexible one on. No probs. Just don't give it more load, or the battery, motor or speed control could overheat, and you will get shorter flights too.