I guess versatility, it could be used without a coupler? Pin grabbers are not very common over here, most machines this size have a tag/ wain roy or the bucket pins on direct. If for some reason I would want to sell any of these buckets down the road, welded pins would be pretty hard to sell but would have a chance with loose pins.
I'm not sure what to say about the s30 option, I thought I was getting close to figuring out what to buy :x
Can the s30 pick up buckets backwards? That's a cool trick of the wedgelock pin grabber.