RE: BCX2:Cutting upper or lower blades.
You may also want to consider a shortened flybar for better response and even less possibility of a blade strike. It lowers the overall rotational intertia of the upper blades. One that works well is for the Dynam Vortex, but can easily be adapted to the CX. It's sold by bphobbies.com and others. Or you can modify your flybar. There are threads on this board that disucss that.