Here’s the MB/sec performance of the OWC Mercury Extreme Pro 6G 240GB SSD in a properly working 17" 2011 MacBook Pro.
This performance is outstanding, the best I’ve ever seen on any Mac, with any drive.
Original 17" MBP headed to Apple
I’m satisfied that the replacement fixes the issue, and so I’ve sent my original unit back to Apple as of today, along with the OWC 6G 240GB SSD, which Apple insisted on reimbursing me for, so that it could be used to test the problem MacBook Pro directly. This shows that Apple is being proactive about researching the issue— which I applaud.