I have a friend who wants to do the same helix thing with his trains. I can't convince him that he is just lookin' for trouble.N are very cool, you can run a very elaborate system on a coffee table, but too much for the little guys. I always wanted to do a 8 level helix with the H.O., got most of the wood cut, but after 2 sheets of plywood cut into circles it got to be too much. I wanted to go up 5', in a 30" circle and out the top of the wall into the living room, then around and down via another helix. TON of track and at least 3 transformers for all that.
Good luck selling your equipment.