Just to let you know I'm running an XB8 alloy shoe on a 1.1 spring and 2 Mugen whites on 1mm springs in my clutch and the engagement is smooth but definate.

The trick to long life clutch bearings is to buy the cheapest you can find, one 5x8x0.5 shim on the nut, bearing, bell, bearing, another 5x8x0.5 shim and then shim it out till there is IDEALLY 0.2-0.5mm of end float under the screw head when tight.