At newegg.ca the Samsung 840 512gb is $600, but lets say that you can find it on sale for $550
And the Samsung 840 250gb is $150 on sale right now at one of my local computer stores.
As you can see, the Samsung 840 Pro writes considerably faster sequentially and randomly.
But from my perspective, isn't it just better to get 2 Samsung 840 250gb, and stick them in RAID 0? It's way cheaper, and I'm assuming that you can theoretically read and write 2 times faster (I know it won't be that much). But thinking about it, the samsung 840 is a TLC (Triple Level cell) and not a MLC (Multi Level Cell) or a SLC (Single Level Cell) CLICK HERE FOR SOURCE. So since it writes 3 bits per cell, I wonder how that will impact RAID 1 performance, and also that makes figuring out the stripe size kind of tricky.