Arch, hopefully you will have the chance to fly your Wind 50E in the next few days. I encourage you to give us all an in depth evaluation based on your flights with the 5s Zippy pack. I'm considering either the Wind 50E or the Osiris. I'm sure at this point either one would be a good choice. Sometimes it's difficult to compare "apples with apples"! The weight of both planes is probably close to 7 lbs. I agree with you, I would prefer to run the 4000 5s and 5000 5s packs I already have. Thanks___Everette