My system is solely 2 channel. There is an obvious sonic difference between CD and some SACD releases. Not all SACD releases sound significantly better than CDs, but the ones that do are well worth it. I would not hold back on SACD simply because you don't have a multichannel setup.
This is why I bought a Sony SCD-1. The redbook playback is very good, it rivals, if not surpasses most of the CD only systems I have heard (Resolution Audio Opus 21, Linn Ikemi, Rega Jupiter, among others). But on SACD, it is at least equal to many of the quality turntable setups I have heard.
I only own around 10 or so SACDs, but it looks as if more and more or being released. With the SCD-1, even if they never release another SACD I am more than pleased with the redbook playback qualities, and I haven't even modded it or added a DAC.
Plus, an SCD-1 looks great, and can be had for 3k new shipped with a five year warranty.