Once I go brushless I will get into the Lipo. From all I read I will burn up the motor and esc in the Mega on a Lipo. My plan once I go brushless is to use the motor and esc out of my Mega for my original Blackfoot. Upgrade two vehicle for the price of one! So I'm trying to keep those in one piece!!I'd say go LiPo instead...
Hobby king Lipos are as cheap as NiMH batteries, and will give more power, and longer run time.
This one is just under $20, before shipping.
Or this one for the same $30 you would spend on that Reedy
Once you go Brushless, those NiMH batteries really start to be a drag on power. LiPo, you will be able to use for years, if you take care of them.