I have built 2 HK 450 clones (see HobbyKing). I am happy with them, and have configured both differently. I have learned a lot from them: How to balance, trim, curves for both throttle and pitch. I would be clone before going real, because you will need to repair a lot until you really get good at it. I bought a few extra kits (less than $30 each) to use as spare parts. I am better at it, so I have lots of spares left, but keep stocking them. I am about to build a third one. Different gyro, head, servos...

Gilles