Not wanting to start an SACD thread. Just saying that if he has never heard SACD it would be a great OPPOrtunity for him to check it out. Will SACD replace CD? Probably not. IMO SACD it is the best digital format at this time and can be a lot of fun making comparisons. At this point you can search through almost 6,000 SACD titles and find some really good deals, on line of course. Also Blue Note and MoFi are coming out with several new releases on SACD. SACD might not survive simply because not enough people care about that type of sound quality, but it will be a niche market for some time to come (vinyl?).
In regards to Sony not including SACD on the lasest Blu Ray player, I believe it was strictly a cost decision. Sony needed to stay around the $300 price range during these tough economic times. It's all about sales. Sony's lastest SACD player was the SCD-XA5400ES. It was just released a few months ago. Two differnt machines.
Having said that, if SACD means nothing to you then by all means look into the S550. But if you think you might enjoy a wonderful fulfilling digital format called SACD, then I would wait for the Oppo and then make your decision.