Kohler k9132 Shower drain

Folks,

Just about to fully launch the bathroom remodel.

The drain listed above has 2 approved sealing methods to the drain pipe: 1. Conventional with oakum and poured lead and: 2. Rubber gasket that is pushed in place from the top of the pan.

I would prefer to use the gasket: What are the drawbacks and or install tips that make this method bulletproof? (The Kohler instruction book seems to be cryptic....) Any other comments or tips on this drain installation are appreciated.

TIA,

Rog