I agree with kelbro. The O/U is technically superior because it has but one sighting plane, but a well-executedSxS is much prettier, balances better, and has a certain quality that the O/U's seem to lack. OTOH, a poorly made SxS can be a real clunker, and lack everything a good one has. Certyain SxS's are really outstanding, such as the Parker, L.C. Smith, and the Win. M21, not to mention the better british doubles. And I have seen some really nice J.P. Sauers and similar quality German pieces.