SSD upgrade on a 2012 non retina 15"

So I have wanted to get an SSD for a while, cost is slightly prohibitive as I need atlas 1T of storage, I have a 750gb HDD right now.

Feed your greed for speed by installing SSDs in RAID 0 | PCWorld looks like 2x 512 drives in raid 0 would be the best. I like the idea of keeping my disk drive but I also like the idea of blasting fast speed, faster than modern PCIe MBP speeds.

Whats the absolute fastest/best 512 or 1T drive, in real world use not just read bench specs. The 2012's are STAT III right? 6gb/sec? Are any 480gb or larger drives SLC or are they all MLC with ECC?

I have thought of purchasing a new 15" retina machine and probably will if they include a GT 950M, but a TB drive in those is a lot of money and they only have the faster Mac Pro style PCIe SSD upgrades for the 2012's. As it sits now they only use 4 PCI lanes where the faster drives and Mac Pro uses 8.

Will Verify/Repair disk/disk permissions auto "de-frag" the SSD?

From that linked post
"Don't Defragment Your SSD

When data is stored on a drive, it often ends up in various parts that aren't all in the same place. This is called data fragmentation. It slows down HDDs because the drive's head needs to move from place to place to read all the little bits of information. This can be fixed using a process called defragmentation, which is built into recent versions of Windows (7 and higher) and OS X. Because the location of data on an SSD is pretty much irrelevant, as it can quickly access any of it regardless of where it is, defragging a SSD is not only unnecessary but bad for the drive as well. SSDs have a limited lifespan that's determined by how much they're used. While most will last as long as you'd ever need, defragmenting the disk involves reading and writing data unnecessarily and those actions will shorten your SSD's lifespan. OS X and Windows should know when you're using an SSD and turn off defragmenation automatically. That said, it's important to remember not to defragment your solid-state drive. It provides no real benefit and can shorten its life.

For more tricks on getting the most from your SSD, check out our guide to taking full advantage of its speed. Now that you have an SSD, certain things—like Hibernation—are much faster than they once were, and are really worth using."

No and don't defrag any brand of SSD.