It seems to me that many bike tourist use SPD pedals? What are the pros and cons for using the SPD vs regular road pedals. Thanks.
I have to ask, "What do you define as a regular road pedal?"
I started with a Look pedal on my first road bike. The one that takes the triangular plastic cleat. Very comfortable to ride in, but the pedals tend to be a little heavy, and you really can't walk around in them.
This is why the SPD type pedals dominated. Shimano makes a road SPD pedal, and a mountain SPD pedal. There are lots of sources for other pedals compatible with Shimano mountain SPD pedals. Personally, I think the Shimano road SPD pedals are a pain because the cleat can only mount one one side, and the cleat is incompatible with Shimano mountain pedals. Even cheap mountain SPD pedals are pretty light compared to how things used to be.
Egg beaters are just a variation on the SPD theme. Different enough to avoid an IP suit, but not as radically new as they might have you think. They might clear mud better and they might be less durable. Or so I hear.
Standardize on whatever pedal you like. I use a Shimano SPD mountain pedals on my touring bike, and Wellgo (Ritchey) pedals on the other two bikes. The Wellgo is compatible with Shimano mountain cleats. I run the Shimano single release cleat on my road shoes (the ones I keep clean), and the multi release cleat on my mountain shoes (the ones I let get dirty).