I think it is cost effective when you only get 5 packs batteries for race purpose, but you may need to use them as practice in the very beginning. When you think the batteries have quite a drop in performance, get another 5 pack for racing, then the older one leave them as practice packs, and so on. You may not need too much packs to racing, since recharge once in a day is a good idea in race, the 2nd charge will give you more power especially with those GP3300 or Sanyo 3300, nomatter who match them.