RE: Sebart Miss Wind S 50E
The ones I have are actually the 20C version, but they only weigh 730 grams even though they are advertised as 740 grams.
I haven't measured the flying time but after a flight with a little fun + P09 + a little more fun I have recharged approx. 3600mAh.
I have the 1010B+ iCharger for these batteries. Had to try it out at that price... (you have to log in at HC to get the good price!) Seems to be a good charger, I just wish it could show the internal resistance during charging, you can only do that after (or before) the charging process with this charger.