I have heard of a few Z plug catches here in So. Cal., but not recently. I did not think the z plug was very big, maybe 6". I trolled 2 crankbaits a while back one was 7" and the other was 11" and the fish came on the 11" bait. I would prefer to use baits in the 9" or bigger range. I have only caught one fish, so I'm just guessing. I also think some of the appeal of the bigger lures is because their jointed, which i did not think the Z was.
Greg silks is still making z-plugs. The one piece and the two piece. I got a few stripers at Silverwood on them last year. Two of my friends used them at Castaic this past fall and got something like 10 on them within a month. Another friend got a small largie at Castaic About 3 days ago in the morning on one.