RE: Are my batteries sufficient
I am in full agreement with Big Max and FW above but if your 6ex system is the 2.4 version and you are using four cell (4.8) flight pack then you need to convert to five cell (6) volt packs and for that airplane as FW noted at least 2000mah's.
I highly recommend that 2.4 only be operated on (6) volt packs which would be five cell packs if Nicd or Nimh.
Just an opinion
John