RE: blade bell/hiller upgrade
I just bought mine the other day. It's a unique setup on the head.
If you're a beginner, I wouldn't suggest upgrading yet. The reason I say that is because the heli becomes much more sensitive with this upgrade. It's a good thing for experienced pilots, but can be a bad thing for newbies. If you barley touch those controlls, the heli moves very quickly and reacts twice as fast.
Newbies, be aware if you have that upgrade and you drop that nose, your heli will accelerate very quickly. Don't let it get out of control!
I'm not sure where you will be able to pick one up online. I got mine in Salt Lake City.
I have only been able to fly it once with the upgrade. I had to send in my 4-1 as well as my transmitter for repair.