You can always have the plated upper, rebored and sleeved, when and or if you manage to wear it out. Heard nothing but positive things as to the longevity of Nikosil plated pistons and bores. There is a small advantage to not running a sleeve, and that is the upper cools a little more efficiently due to the better transfer of heat via the homogeneous construction. Quite a few properties of steel and aluminum alloy are different. Especially concerning temps. (disclaimer)IMHO
