2650 yen gets you one of these. Pretty cheap.
I really can't justify the Lipo direction.
The only way I'd upgrade would be to go the whole hog.
Yokomo D-MAX twin lipo packs, new ESC and Brushless engine.
The only thing I am considering at the moment is a new Handle. 2.4Ghz FHSS systems are getting cheap.
Bye bye crystals. Even Yokomo are bringing one out. KOPropo has one that interfaces with MiniZ. cool.
But for now, I'm satisfied with my setup.