I use mtn pedals and shoes (spd 2 bolt) on all my bikes. The first reason is for consistency, I like having one pair of shoes for everything (bikes, spin class, etc.). The second is so I can walk comfortably off of the bike when I want. On long solo rides, I like being able to stop and walk around, get a bite to eat, etc.

I can't really speak to articulation, but I think the biggest advantage is being able to power through the whole revolution of the pedals. Being able to stand up and hammer when going through intersections or steep climbs is huge.

I use Shimano PD-M540 pedals and Specialized MTB shoes. Would highly recommend both.