If a Surround Sound system isn't set up properly you can't expect to have much of an improvement in sound with SACD. But if you set it up correctly, and don't try to do it on the cheap, the results can be astonishing. Of course, it always comes down to how the original recording was mastered. There are many redbook cds that sound better than many sacds.
To really hear what a good sacd can do you need to use headphones. To be honest, no integrated amp has a headphone amp worthy of great cans. For that you need a dedicated headphone amp and the good ones don't come cheap. My current amp is a Woo Audio WA6 which is very reasonably priced, especially for vacuum tubes. Paired with Sennheisers HD800 the sound is thrilling, lifelike and exciting. Of course, then there's the front end: you have to have a great cd player, but no one needs to spend thousands for some of the really exotic labels. I have a Sony ES series connected and it sounds great. Try a redbook vs. sacd of the same recording and you'll be amazed at the difference. The multichannel sacds have no value.
For movies and sometimes music, I use speakers. In a typical room (NOT what you have in an audio shop) the ambient noise is going to make a difference. A high quality receiver is not terribly expensive. I'm currently using an Onkyo that is everything I need - enough power to make Lord of the Rings take off, more connections than I'll ever use, and built like a tank. Any good bluray player with sacd ability is fine. Now with sacds the sound can be amazingly lifelike, powerful. But it's a matter of are the speakers (especially the surrounds) set up and calibrated correctly. Sometimes, the surrounds only add some ambience, sometimes, more, especially in movies. With a good recording, crank the volume up, have a good bourbon in your hand and wallow in a sound that is usually only experienced by a conductor standing on a podium.
I am old enough to have gone through every attempt to make sound better in the home: from mono to stereo lps, then came quadraphonic, the ill-fated CX lps, tape formats from 1/4 inch, cassette, to the forgotten Elcaset, then finally cds - and on to HDCH (still the best sounding disks I've ever heard), Dolby Surround, SACD, and now BD-A. I have not played with the downloadable formats and won't. The dream of a sound so life-like and accurate that it sounds like "you are there" has never yet been reached. And I've listened to superb $100,000 Krell systems that are still not there, however great they sound. But there is one format that could have come closer than anything if producers had just promoted it and if there had been an audience large enough to support it: and that's binaural recordings. The few that I have convey a sense of being there that is simply incredible. It's really too bad that when the great cd era started some 30 years ago that binaural mics weren't set up at the same time as the other mics and have that option. With sacd coupled to binaural the sound could have been nothing short of miraculous.
It is interesting that there are few companies left doing sacd, and they don't even do it on all their recordings. Maybe the audience isn't large enough and the modest increase in sound quality just isn't worth it. Besides, with most people getting their sound on cheap earbuds and mp3-like players and phones, what does it matter? HiFi is going away.