Bite the bullet and go Lithium Polymer directly. Later on down the road once you feel safer with a "hotter (lower turn)" motor, you can upgrade to that motor without worry that the Lithium Ions will not offer a high enough discharge to power that motor. If you go Lithium Polymer right off the bat, you know you're safe in the battery department for whatever you decide to do. Plus, Lithium Polymer's are easier to install since they're square flat packs, rather than round cylindrical cells. It takes less cutting, less wiring and a little bit less hassle.
Whomever says Lithium Ion is more safe than Lithium Polymer is incorrect. They're both just as dangerous and need to be treated with respect and care. Both of them can go "BOOM" very quickly and unexpectedly when treated horribly. They're still both Lithium technology, they're both just as mean.
