When I get back stateside I'll go on the hunt to see can I borrow a Dual 4 Type R to test that theory out.
If I can I'll take my M6mkII (same as a D6) out of the box it's in and drop the Type R in its place. On the same power in the same box off of the same source I'll see if there's a 'drastic difference' in my listening space.
Until then I call BS on a blanket statement such as that.