"First, I like to be able to walk in shoes when I get off the bike"

Thats what mountain or trekking shoes are for. Ive spent full days at the shop I work at in my cycling shoes when forgetting my regular ones. It was fine.

"Second, I don't believe the touted "efficiency" claims with clipless"

Know anyone with a powertap or SRM crank? switch pedals and check your wattage. You will notice substantial differences. If I have time in the next week or so I could probably give you some solid data on attacking a hill with either pedal system and noticing the difference but would you believe me?