I've got a few of each. Sonicly, I consider them interchangable. The multichannel thing is more of a "special treat" than anything else. Someone on this board once made the comment that if you sit down to listen, sacd/dvd-a is worth it. 20 years ago I sat and listened all the time, not so much these days. Which brings me to my little rant.
The one place where I and everyone else sits and listens, almost always with surround speakers already installed, is the car. You cannot get a sacd/dvd-a car player that does multichannel,at any price. You can get a bloddy video setup complete with dd sound and screens all around, but the few that play dvd-a downmix to 2 channel, WTF? Stupid bastards, anyway. DPL2 is a big (and expensive) deal in car audio. Am I the only one who sees the boat being missed here?