Redbook layer on SACD - good enough?

"is it common to manufacturers to make CD layer worse then SACD layer intentionally?"

Dunno. They have been accused of it but, aside from the DSOTM SACD, I know of no evidence.

"And more important is SACD being played on SACDP sounds lot better than DSD layer to be played on Redbook CDP at the same price range, or even more expensive."

How do you play a DSD layer on a Redbook CDP?

Buy it. No difference unless the manufacturer intentionally wanted to make one.

In addition to all his other comment with which I concur, Ben Campbell wrote: "So if the information on this is correct then the DSD process can be used to make CD's as well as SACD's."

Only if it is converted to PCM as it usually is. I was questioning 'lafish' saying that he had played DSD on his CDP.