I read two questions:
- How secure is the Intel SSD encryption ?
- Are there any known flaws to the full-disk encryption of [specific models]?
To address the first question about "how secure" it is...
As with any security the answer is always relative.
Sector-based (hardware) encryption on-disk is orders of magnitude more secure than software based data security. Why? Access.
I worked at a data security software company for several years that had some of the best root-kit and Windows NTFS hackers in the world. After many attempts, they established and conceded that hardware/disk/sector based encryption was much more secure (and less complicated) than software. Software can be circumvented and fooled, especially the lower in the stack you get (all the way down to the BIOS). Hardware based encryption by Intel and others is device-based and as such I am not even aware of a BIOS hack that can get under it.
The military and secret data organizations regularly require disk based encryption to remedy the "stolen laptop" problem. Short of removing the disk drives and putting them in a fire-proof safe (which some organizations actually do), device based encryption from Intel and others is probably the best way to safeguard data [completely] at rest.
I have not read of any flaws in the design of such implementations and I suspect if they were found in the wild it would be a big headline. NIST and other groups strongly endorse and encourage use of this technology for securing data at rest.