First of all, I wouldn't recommend this build for anyone. It's a little bit silly and not well-thought-out, as I have been tinkering with it for the last three years.
The last time I altered it was in the summer of 2014, when the C: drive imploded and I needed to replace it. I took this chance to perform other upgrades. I switched the case from a puny, cheap mid-tower to the monstrous XL R2. The C: drive was changed from an ADATA SX900 (imploded) to a Samsung 840 EVO. The two mixed-size WD HDDs (still working) were replaced by two 2TB WD Greens, which are in a RAID 1 configuration. I considered changing the motherboard as well, mostly for a board with more SATA connections, but that wasn't worth the price.