Mark,

If you have an ESC that can handle the radio power required and will support a 10s input, you could do this but I wouldn't recommend it. Usually you can't use the ESC BEC(if there is one) to do this when we are talking 8-10s batteries. When you read the instructions for the BEC it usually places limits on the number of cells you can use and also the available current will drop with the number of cells. Since the BEC is embedded in the ESC you cannot use the balance connector to supply the BEC with a lower input voltage.
If you are using a motor battery that is 3-4s total it would work but this is probably a cheaper smaller model and I usually use only the BEC as a single source power input for the receiver and batteries in those planes. There just isn't the same amount of money and effort in the model.

One advantage of this dual system is the use of cheap batteries. Go someplace where you can find 350 2s batteries for less than $10. Right now HobbyLobby has 350 2s 30C packs on sale for $5.99. Hobbypartz and hobbyking are other sources.

Cheers
John