Don't listen to people talking about "safety issues" about lipo. They usually have ZERO personal experience with lipo. They are only regurgatating a very old and tired story about some guy using HOMEMADE lipo packs and severley over charging them. Well guess what, severely overcharging NIMH cells will also present a "safety issue".
Furthermore, I've crashed my lipo powered car MULTIPLE times. Nothing bad ever happened.
Anyhow, if you want to check out lipo, visit: Thunder Power Batteries