RE: BCX2:Cutting upper or lower blades.
The cool thing about the upgraded flybar is that you can move the weights in/out on the flybar shaft. I use a digital caliper to ensure they're exactly the same distance out on either end. I can move the weights about half way in, and I actually like the response I get now. Forward flight is a lot more responsive, too. With the stock flybar, after a bit of forward flight, the heli wants to stabilize and hover again. Using the new flybar with moveable weights gives you some ability to compensate for that natural desire to stabilize and hover. You can actually fly the thing. Hopefully it'll be good training for a future upgrade to a CP or Trex. It's a lot "touchier" with the reduced (weights moved inwards) flybar, and it also helps to teach one to avoid "over-controlling." No blade strikes yet.
PS: The ball/link arm that comes with the Dynam adjustable flybar won't attach correctly to the "ball" on the upper blade of the CX/2. Different diameters. You'll have to unscrew the lower link from the stock flybar, and screw it onto the new flybar upper link and it'll work great. Of course, you'll have to play with adjusting that link so that the upper blades track properly. Not a big deal, and worth the effort. If you buy the flybar from bladecxpro.com, he's already unscrewed and removed the lower link portion from the flybar. He knows it won't fit on the CX. Use your stock lower link half in any event. Also, my brand new upgraded flybar came slightly bent. Roll it on the table (with weights attached) and make sure the bar is straight (and make small adjustments if necessary) before installing on your heli. Don't assume the bar is straight, just because it's brand new. This flybar is probably the best "upgrade" you can give your heli, as far as handling and response.