Having cable as made things much easier for me. While I was in Australia I was dialed up with 56k and there were a few key differences:
1) On 56k, if I collided with someone, I would get credit for the kill nearly every time (if it was a HO).
On cable, if I collide with someone, I never get the kill.
2) On 56k, I hosed people down (due to the damage being delayed) - I just wouldnt stop shooting until I saw a part fall off.
On cable, I can pop a few rounds into someone and see (pretty much instantly) what damage I've dealt.
3) On 56k occasionally it would look like I got away without a scratch in dire situations, only to be blown to pieces a few seconds later.
On cable, this never happens.
4) On 56k, sometimes I would plow someone with rounds, only to have someone else shoot the con a few seconds later and get credit for the kill.
On cable, this never happens.
There is a clear advantage to having better ping. The game is still wonderfully playable with slow connections, but anyone who says it's better (or even the same) is mistaken.