Sounds like you want Super Record. I agree with the other posts about using a Chorus cassette for durability. I think the Super Record will be as durable as Chorus. I've had 2 bikes with Chorus 10, one has 43k miles and the other 22k miles. I've just replaced the usual stuff, cassettes, chains and brake pads. Big chainring on the 43k mile bike. I'm pretty sure SR would last as long, but even if it's 10% less you'd still get > 30k miles out of it. And I keep my bikes a long time, so you'd probably upgrade sooner than you'd see any durability problems?