I have a similar setup to yours, only I have no Z4000s and I am not at all familiar with them. I currently have only 2 main lines and one TIU powered which is powered from the Aux port by a Z500. I am using the TIU's 2 Fixed channels, each powered separately by a Lionel PH-180 brick. My plan is to add on to my layout with 2 more PH-180s, 1 on each Variable channel that will both be set to fixed. I operate command control only, no conventional.
I think you will have basically the same thing, but substituting a Z4000 handle where I have a PH-180. I don't see anything wrong with that and I think you will be just fine and it should work well. I think the Z4000 handles will have to be manually powered up each time you turn on the system, but as I said I am not that familiar with the Z4000s so I don't know for certain how this is done?
Purchasing Barry's book will explain a lot and I think you will have a much better understanding about all this with his book. It's well worth the money and then some. I believe he even touches on the Z4000s in the book as well, if I remember correctly. I believe he explains powering the Z4000s on start up as well. You will definitely want to use the Aux port to power the TIU since you are using more than one channel. You can run quite a bit from one TIU, depending on how you want things setup. Barry's book goes into that as well.
