Is the Zetec much easier? Still needs the mount messing with. The RS lump mates up to gearboxes fine, so not harder from that point of view.

If I was fitting a boggo standard engine, or a lightly modified one, it would be RS2000 over Zetec any day of the week. More power to start with, and 175bhp isn't hard at all. If I was going turbo, I'd go Zetec, as there's so much knowledge about, but for aspirated, there is little between the I4 and Zetec. People are just scared of the I4 for some reason.