I have used the xDeep Zen since my 5th dive and never looked back. Also I'm looking to get a NX Project for doubles when the time comes. I had looked at the ghost but determined that I was not going to travel by plane as much as I preferred to have it a little more robust. I wouldn't hesitate to buy it should I start to travel more and need to lighten up the load. Unfortunately I do not have experience with the two models you mentioned.
If you have questions then pick up the phone and call Tec Dive Gear. I believe it is the US distributor. Sebastian has been very responsive on all my questions usually providing information that was useful that I did not know I didn't know.
Thanks for the info. I will contact Tec Dive Gear.