Redbook layer on SACD - good enough?

No. How could it? But it's likely that the mastering is different on the different disks--and there's no guarantee that the best version (or, rather, the one you would like best) is on one or the other. If both the CD and athe redbook layer of the SACD used the same master, they will likely sound identical.

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

DSD layer from SACD Hybrid wins over Redbook CDs. 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.

This is a fact.

"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?

Lafish: I've got SACDP some time before, and then discovered that mastering quality on available SACDs isn't as good as on good CDs (IMO), so I decided to get a good CDP instead. When SACD will be mastering with XRCD quality -then it won.
Kr4: is it common to manufacturers to make CD layer worse then SACD layer intentionally?

yeah, but the existence of the transparent layer could pose a problem for the cd player's optical pickup, no? The cd pickup (780 nm) would have to read through the transparent layer designed for the 650 nm SACD pickup, no? might that affect the sound quality of the transport? I don't know for certain, I am just asking. Or is it totally transparent?

I would imagine this would have been discussed to death on AA.

KR4-I have the new Miles Davis box set The Complete Jack Johnson-it was mastered using the DSD process but it is NOT a SACD nor hybrid.
So if the information on this is correct then the DSD process can be used to make CD's as well as SACD's.

"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.

It's been my experience with hybrids that the mixes are identical on the different layers-it's just the actual replay formats that are different.
As such any difference is down to the superiority or otherwise of the format.
I've found the Redbook remastering all recent hybrid SACD's with the exception of DSOM to easily beat their previous incarnations on CD.

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.

What about Aroc's comment:"The cd pickup (780 nm) would have to read through the transparent layer designed for the 650 nm SACD pickup"?
No matter what, SACD layer cannot affect focusing, whatever, of CD layer?