rabindranath72
Explorer
As we moved to 2e from BECMI, we started with the analogous rules, and gradually added most (if not all; memory is failing me now) optional rules. One thing we practically never used was individual initiative; rather, we used group initiative modified by each player (which is another optional rule.)
When the PO+C&T books were published, we added a few things (the simpler of the critical systems, and the revised NWP check system), and then later added more stuff, but the campaign collapsed and we stopped playing altogether, until we moved to D&D 3.0; we loved the ideas behind the PO+C&T stuff, but the execution left a lot to be desired. So when we adopted 3e, we saw it as a sort of "cleaner and consistent" 2e+PO+C&T. If I had to run 2e nowadays, I'd keep to core only.
When the PO+C&T books were published, we added a few things (the simpler of the critical systems, and the revised NWP check system), and then later added more stuff, but the campaign collapsed and we stopped playing altogether, until we moved to D&D 3.0; we loved the ideas behind the PO+C&T stuff, but the execution left a lot to be desired. So when we adopted 3e, we saw it as a sort of "cleaner and consistent" 2e+PO+C&T. If I had to run 2e nowadays, I'd keep to core only.