Dunno why I hiccuped!
BTW, one of the biggest arguments against the notion that the Roman defenses were predicated on the Chinese defenses is that the Roman frontier defenses were never systematic in the same way that the Chinese defenses were. More importantly, we do have considerable records of the development of the Roman Limes and of the Great Wall and to my knowledge there is no record of the Romans acknowledging the alleged Chinese origin of the idea.
Finally, we have a good sense of how familiar the Romans were with China and the Chinese were with Rome and it's quite clear that they had nothing but the very dimmest conception that one another existed.
While I wholeheartedly agree that there's not likely any connection between the development of walls, the Roman Empire and China had continual trade links, both overland and (more intermittently) by sea, usually by go-betweens, but occasionally directly.