I've got a pace-edwards Jack Rabbit tonneau cover on my Tundra. Love it. It does lock with a rubber seal against my tailgate.
If I'm driving at high speeds (i.e. interstate, etc..) I can hear it rattle a little bit only if I put the back window down. It's not bad and I can't hear it at all with the windows up.
Pace-Edwards and "Roll-n-lock" are the two best brands IMO for locking tonneau covers.
JL