For the average PC user I really don't see the increased cost of the Pro being worth it over the Evo. The real world performance will be negligible. The real difference is in the warranty and rated life, but for most users this will be meaningless. For example I have two PC's running 250 GB 840 Evo's, they have been in use for 18 months. Both of these PC's are used daily for gaming, photo and video processing. So far the total bytes written on these drives are 1.22 and 2.05 TB. At these rates I will reach the 40 TB rating in 49.1 and 29.2 years. With SATA Express and M.2 interfaces becoming more mainstream most users will upgrade to faster drives long before approaching the write ratings.
If you are a professional photographer/videographer or do high volume processing than the increased cost is justified.