The Z1000 is limited to 100 Watts...whether that be from the main track output or the 14V Accessory output. While it is true that powering the LEDs with 18V consumes more power than 14V, the difference is small compared to the massive power savings in replacing the incandescent bulbs. Plus, it sounds like re-wiring the switches for Accessory power would be a nightmare.
I could get into the finer points of operating the actual switch machines at the different voltages, but since you've been using the track voltage, why mess with success. For example, if a switch jams midway thru travel it will consume a huge amount of power and potentially heat up and melt something. The meltdown will occur much faster at full track voltage than 14V Accessory voltage. But like they say, trains are NOT meant for unattended operation.
