Doc

A123's are heavier than LiPo's without question, but they are more stable and able to be re-charged at 10 Amps, largest cell available is 2300Mah so you will probably need to put two packs in parallel to get decent duration, which increaces the weight dissadvantage even more, Can't comment on the Skorpion motors as I do not have any, however after going through quite a few Castle Creation speed controllers I will not buy them again, I now only use Hacker or Jeti (Jeti make the Hacker speed controllers) I have pulled on climb out over 100 amps on 10S LiPo's on a supposed 90 amp Jeti controller without complaint.

Hope that helps.
Mike