Just a few things to consider.
First, running without a center speaker is not the the same thing as not using the center channel of the mix. It is completely possible to mix the center information back into the fronts without leaving the analog domain. I have a center, but I thought I should point out the distinction.
Second, yes there is a day and night difference between CD and SACD. According to normally reliable sources this is due to fairly aggressive EQ and other processing that Sony adds during the mastering process.
Kinda like why DTS sounds so different from DD too.
Finally, and this is just my own opinion, the big advantage of DVD-A/SACD is the multi-channel format more than anything else. The bigger samples and/or higher rates make the systems easier to implement well, and so that is good, but offer no intrinsic advantage in absolute sound quality for humans.
That last one is very controversial and I don't expect many here to agree. It is just my opinion, based on solid engineering priciples. Anyone who listened to the 'soundhound challenge' CD got an extreme example of this first hand.
A lot of the bad rep CD audio has stems from two places:
(1) It's hard to implement a really good digital system with a upper frequency limit so close to the Nyquist frequency. Not all implementations were very good, especially early on. Ironically a higher sample frequency would have made implementation easier and possibly fixed the 'problem'. It's like the sample rate argument is right for all the wrong reasons.
(2) A lot of 'Hi-End' folks just couldn't (some still can't) get their heads around how it works. They are often respected in the community and their opinions carry some weight.
Just my $0.02 and YMMV, etc.