Are you referring to BraveSpear's post? That doesn't look wheeled to me. It's got tracks.

Depends on the terrain you're trying to excavate. You want to take the top off a flat area, use they type you linked to (which is more of a bucket-belt). You want to open up the pit/strip by cutting out the side, you need the wheel type.

Every bucket wheel excavator in the world is custom built for the terrain it's going to operate in and the yield it's required to produce.

Oh... I see you're talking about the excavator scoops. I'm going to go sit in that corner now. :D --->

and don't you dare come out of there until you've learned your lesson, young man!!!! ;)

I'd hate to get stuck behind it on my commute :p