hey paul, have just seen this. Snapper-wise I'm getting a few fish with "suspending" (as apposed to floating) x-raps in small sizes (designed for fresh water) off the rocks, i'm finding it key to spend a bit of time going full speed/lots of vibration, then slowing right down/barely wiggling, the full speed gets them interested, the slow down is when they bite, but the lure must either sink slowly or suspend when you slow down, the snapper that are following/interested will back away and not bite if the lure starts floating up. I picked that up from a talk craig wrthingon gave on his experiences with snapper on flies. becuse most of these sorts of lures are designed with fresh water, the suspending models often need a little bit more weight added to stop them from floating up, I've been adding split-shot to the hook attachment points which works, but they fall off when fighting a fish most of the time.
there are some little sinking rapala CD7's in NZ which should work well by my reckoning, i'll hop-to and pick-up a couple this week i think.
....of course none of this is "the most effective" way to catch a snapper (or close to it), but fun to play with all the same.