Hello, the method using a DPDT centre OFF Toggle switch is a method I have been using for many years without any problems, it has an advantage that if your setting up a multiple unit with more than one decoder they are all programmed as one, also no need to handle your locos being moved for programming. Just run them in and out of the siding. The one thing I would say is Label the switch as to show which supply is powering the piece of track being used for programming. I use P (in red ) for programming & M ( in black) for main track supply plus OFF for no supply.