Having owned an SD I can attest it wears thicker than pre-big lug Subs. It seemed like they added thickness to the case, crystal and case back. It wears heavier than the Sub. One reason why I chose an SD as my first Rolex was an aversion to the date bubble and the notion that it would be easier to tell apart from fakes, as my assumption was that fakes just added a valve to the Sub case. I've no idea if that was true after all, but I found the watch heavy and too blingy for my taste wine the shiny dial and markers. Plus I like date bubbles now.
It wears a bit bigger than the older version Sub, but about the same as the current version Sub or GMT. But the thing that really bugged me about the SD was the hump on the back. I found this a bit uncomfortable.