OAB Implementation - Pre or Post tax set up at plan or option level

We are implementing OAB (from OSB). In OSB we have the pre and post tax elections done at the plan level -

For example, select:
Plan - Dental Plan Pre Tax
Option - Employee

In OAB we are considering setting pre and post tax at the option level -

For example, select:
Plan - Dental Plan
Option - Employee Pre Tax

Is there a difference between these two methods and does it matter which route we choose? Would the only difference be what the employee would see in self service (with the first way they see more plans and fewer options and with the second way they see less plans and more options). Is there something else we need to consider?