Definitely not a stupid question. However, going with the higher voltage pack isn't going to give you any longer run times, and here is why. Your original pack is rated at 1400 Mah and the pack that you want to go is is only rated at 1300 Mah. Comparing the two packs with both putting out approximately 5 volts (4.8 for your original pack and 5 volts adjusted on the new pack) your original pack has the higher capacity as it can supply 1400 Mah. In addition, by adding the BEC you are adding one more thing that can go wrong in the system. If you are looking to increase your flight times go with a pack with a higher capacity, not higher voltage

Ken