I am trying to decide if i should go lipo or nimh on my granite mega. I know lipo is better in almost every way. The only problem is cost. Can you get a good lipo battery and charger for under $50?
Having said that, upgrading to LiPos and the BLS is only going to buy you a few more mph than a 7-cell NiMH pack. If you don't have the LiPos or BLS combo, I would just stick with the MEGA and NiMH. If you want to increase your speeds and are ready to spend, I would look at going straight to the BLX-level setup, in which case I would recommend looking at the Castle Creations or Hobbywing ESCs as they have more tuning options, or check eBay for BLX systems that people are selling after having moved to a CC or HW ESC.
Normally the MEGA motor will be fried soon on 2S only.
But again this should not happen to the MEGA esc. It is lipo ready. So I would suggest to claim warranty.
Cheap lipos which are good are available. Depends on your location. Check hobbyking for example.
But I would not save money on a charger. That is a long term investment