I splurged on original purchase and went with the 1 TB SSD for this MBPro Retina Mid 2014. Still getting my files situated from the old system. The TiimeMachine is taking forever to do its backup (I guess the TimeMachine didn't see that the basic system software/apps/etc. was the same. Guess it knows what it doing. Have got my self an external disk I've made a "mirror" of the boot disk using Carbon Copy Cloner. Have a lot to do before I can "play" around and see the differences from my old reliable MBPro 2,3, early 2011; which had been modified a lot and was very spiffy with the 256 GB SSD as the boot drive.
Having the 1 TB SSD in my new MBPro Retina, partitioned as my old system was, has a very good investment. Need to look around to confirm that there not many user internals that can be modified. But then again, maybe I should stay out of my new MBPro for a while. :)