.......And I use four small transformers for my four livingroom lines. (3-1033s & 100w Marx)
Another room, 2 lines, a prewar Z for grades w/blocks (4 throttles), and a KW (1 throttle is track, 1 is lights & turnout coil power for all lines) . The Z and the KW lines also share a 1 track mainline block along a wall. (on Z#4)
All small ones were $20 or less and rightly sized for a 4.5x9. Each has a whistle control and direction lever.(well, not the Marx...but that runs Marx mostly anyhow...no whistles. 1033 #4 is now by itself in a bedroom) I dont know about the new ZWs, but I have more whistles and easier direction change than I would have with a ZW, for about half the cost, maybe a third.
(not knocking, had a ZW presented itself at a low price, I would have gone for the extra wattage; My favorites oldies can be run wide open throttle with a 1033. and two of them, if pulling a really heavy load, may even stall or trip the breaker after about ½hr.
That's right, 4 throttles 100% open, and no 100 smph running....kid proof 
Except when I WANT to go too fast, then I just pluck a few cars off 
