In the end I went with the most expensive but also the fastest option: #1 which was the Mercury Accelsior PCIe based SSD hardware RAID array (RAID 0 by default which I will keep) in a Mercury Helios Thunderbolt PCIe chassis. The main reason was because it was the only one that mentioned it was bootable (and made a big deal out of that fact).
I paid $799 for the 240 GB model (it's 128 GB X 2 minus the unusable amount...a nice touch for the seller not to count that). It's got a lot of technology built into the card including processors and cache etc. to monitor and control the hardware RAID array including extra error checking and load leveling/balancing. Also it's theoretically upgradable (each drive is called a "blade" and while they don't yet sell independent blades they may in the future). Also the PCIe chassis is an extra bit of the investment that could live beyond the SSD, just like the whole arrangement could live beyond the use of my iMac itself.
This is a great review on it where they say it's "really fast. Ridiculously fast."
A guy on youtube has a (somewhat boring) video of his Mac Pro taking 3 minutes to boot and launch paint shop pro with his hard drive and then after setting up one of these it cut down to 15 seconds! Crazy balls out fast.
This is the sellers sites for;
Of note is that if they didn't offer the bundle discount and if it were not so much more expensive I might have opted for this much more attractive chassis.
Or for even more and larger chassis with multiple slots and supporting larger sized cards.
These chassis got me thinking about the possibilities with thunderbolt. Now any iMac or MacBook can be as capable and expandable as a Mac Pro...there are even developments with video cards in one of these things! I do wonder if it would be possible to take a MacBook Air and hook up a thunderbolt PCIe chassis with a high end graphics card with the display on the internal monitor?
If I was one of these manufacturers, or even Apple, I would consider making a full on chassis with PCIe slots and storage areas, etc. I really wanted a Mac Pro but they were so old...now I can get some of that goodness piecemeal, though for a price. :-)
I get the device about a week from now and will post back my impressions if anyone is interested.
The easiest way would have been to create a time machine backup before replacing the drive, then use Migration Assistant to import your account, apps, etc.
However since you replaced the drive already, you will need to get an USB to sata connector, or external enclosure, to connect the old drive in order to access the data.
At this point you have 2 options
1 - Run migration assistant and point it to the external drive. It should see your old account and allow you to import everything. (Sometimes this fails, see http://www.hardturm.ch/luz/2014/02/fixing-os-x-10-9-mavericks-migration-from-external-volume/)
2 - Manually copy the data, or the entire account folder. The original account will be under the /Users folder on the old drive. You can copy the full account if you wish, then use system preferences to create a new account with the same shortname; it will prompt if wish to use this existing folder for the new user account. However, if you decide to try to copy manually you may run into permissions issues. You most likely will have to reset permissions on the folders/files but you can use BatCHMOD to do this (free). Be warned that I would not mess with permissions on the original drive in case of a problem, only work on the copies you make.
Best Answer
If you've got a functioning OS on the SSD then you should be able to set this as the boot drive in System Prefs. Boot off it and then use Disk Utility to unmount the 1tb drive. Test everything with the 1tb drive unavailable. If everything works fine without it then you can remove what you want from the 1tb drive.