Surprised you found the Shinkos to be slippery, Peter. I thought they were supposed to be sticky and short lived.
I'd include Continental Road Attacks in the discussion. I found them to be a good ride, but sold that bike after only putting a couple of thou on them.
I have had a good run from Metzeller Z6s on the 1100 and 1300, so can recommend them.
Walking along the line-up at the FarRide in Eungella I could see a high proportion of PR2 and 3. Those guys know their gear, so I'd have to give Michelins a tick.
Haven't heard many good things said about Bridgestones or Dunlops, but both have their fans.
When it's all said (and done), I'd have to agree I'd prefer reliable grip to longevity of distance. And I'd have to say none of Z6s, Road Attacks or PRs have let go on me. Then I don't push them in the wet- too big a sook to want to know how far they go before they let go!