My humble opinion...
1)SA-CD is worth it because better care is given through out the entire recording/mastering/transfering process than it is with CDs. In other words, you will find a higher % of bad sounding recordings (i.e. "re-mastered", or mastered for radio/car audio, not hi-fi) on CDs than you will on SA-CDs.
2) Everything is recorded in hi-rez these days, so it makes sense to not compromise the master quality by transfering it in 16/44.1. So we are kind of forced into hi-rez playback.
3) I asked myself the same question a few years ago. My playback system consisted of Yamaha dvd player feeding spdif to a MSB Link III DAC. I was wondering if a new generation yamaha blu-ray/sacd player would sound better than the MSB. The answer is YES with CDs, and obviously yes with hi-rez material, either on thumb drives or on hard disc... blu-ray, 24/96 and dff files.
I got the BD-s677 for $250 to try, and it is MUCH better in everyway, more natural/fluid than the MSB. A definite keeper at the price point.