RE: heli gyro for cpv3
I have never had any luck with the brushless tail, many others have had great success. I went with belt drive tail, but thats another thread. Try looking over at RCgroups forum for the helimax Axe CP thread. You will find a group of great guys experimenting with the brushless tail right now.
The gy240 is definitely an improvement over the stock 3 in 1 once you get the electronics sorted out. The stock 3 in 1 is ACP's weak link IMO.
Some pilots are also having success with the new HMX4000 gyro... search the threads for more info