Follow Up: the Crucial SSD has arrived, and is now installed in the main bay of my 17" MBP Late 2011. It is working very well, it is approximtaley 2.5 time faster than the original SATA-2 SSD, which has now been moved in the optical bay.
I still prefer to leave this unit as the system disk (I suppose that it is more reliable, for now).
Indeed I am very happy, my system is now flying, 1.2 Tb of storage, all SSD !!! And 16 Gb RAM...
Even if it is 2-years old, I do not think you can find a faster laptop, with such a nice antiglare 17" display nowadays, and capable of running both Windows 7 64 Pro and OSX Mountain Lion...
If only I could install a second Crucial M500 in the Optical bay, I would have a 2TB-sysem in raid-0...
But this is unlickely to happen, the optical bay cable is not good enough for SATA-3...
On the other hand, there is little chance that either Crucial or Samsung release a cost-effectiv 1Tb SATA2 SSD. And these are substantialy the only two contenders in the market capable of relasing cost-effective 1Tb SSDs...
So I suppose that my system is now at its maximum possible confguration ad performance, I hope it will last until something similar appears again on the market.
Currently if the laptop is stolen or crashed, it would be very difficult to replace: Apple does not produce anymore 17-inch laptops, nor anti-glare displays...
The Retina models have significant problems for my usage (small display, glossy, not-native resolution operation under OSX, just one SSD not user-replaceable, no Firewire port, no Ethernet port, no Exresscard slot, no expandable RAM).
I think that the history of Mac laptops was like a parabolic curve, and the maximum was hit with my one. After this, the only significant improvement was the USB3, which indeed I also have thanks to a 20-USD expresscard. In the meanwhile, so many good features have been removed...
It is good that these new excellent 1Tb SSD units can now be emloyed for revamping the 2011 models, extending for another couple of years their work life.
But it is bad that Apple does not recognize the need of these professional machines by power users like me.