I've only really noticed it going in to Perth on final approach, probably in the last 1000' feet or so before touchdown, fully configured as far as I can tell. Perth tends to be gusty doesn't it, so maybe it's related to that. Some of my colleagues have commented on it as well. It's distinctive enough that we assume it's something to do with the aircraft type as it's not something we've experienced on other types. Don't take it as criticism, I'm just curious as to why it feels less stable in speed to us sitting in the back.