Hello.
A couple of comments:
1. A typical F3A 10s li-po pack weighs more than 1.0 kg. for 5Ah capacity. The TP Extreme 5000 weighs approx. 1200 grams, others may be even more.
2. Even if you use a faster spinning motor in combination with 8s 123's, you are carrying significantly less "fuel" than you do with 10s or 11s, so the flight times would have to be shorter. (Assuming that you are using the same power (i.e. watts). The amp. draw would be higher, and you would empty the packs quicker.)
3. If you by "continuous current" mean average current, then this will be significantly lower than 50A. 24-25A is more likely. (But max A may still be 75-80A)

Regards,
Magne