I was wondering the same thing John. As I understand it the DCSRC watchdog signal lasts several seconds after startup, so whether the PBW triggers once a second, or up to once every 5 seconds or so is immaterial. Hopefully Stan will clarify his intentions.
Happily I have a DCSRC connected now at the rotary switches for my main yard and t'table, so PS-2/PS-3 engines now power up dark and silent until I start them up. Will modify it to continuous PBW operation once your kits are delivered. BTW, did you manage to get the kits done up and shipped yet? Not that I am in any big panic.
Rod