I suspect it's a case of either/or. Sometimes it's lag, sometimes it's pad. Lag seems a lot more profound - I've seen people who seem to actually crash into the gravel traps then there's a mysterious, high pitched "WHHHHHEEEEE!!!!" sound and they warp into position in front of me. I think that's lag. Then there's people who seem to "wiggle" on every corner - my guess is they're driving with the sixaxis. Sometimes I just can't tell for sure.