I`ve switched from installing Cricial M4s to Samsung 830 and 840s (non pro).
So far, so good (I`ve installed about 15 x 250GB 840s, they all been fine and very fast).
Is the Pro worth the extra ~£50 (for the 256GB version) ?
I think not, but if you think the TLC NAND and slower write speed of the non pro will be an issue, then the Pro would be a good SSD to get.
BTW, I recently installed my first 120GB non pro in a PC build, and that has even slower write speeds than the 250GB version. The machine was anything but slow !
I reckon the Samsung 840 250GB is the best bang per buck per quality SSD around at the moment.