I wouldn't exactly call the MX500's read/write speeds of 560/510 MB/s and 95/90k IOPS "catching up". It surprised me when I read that so I went to double check. The MX500 is not even as fast as the 960 EVO (Actually, it's less than half as fast) much less the 970, and it's more expensive, at 121.99 being the least expensive I could find one for, although the double storage space is nice, users looking for fast drives are more worried about performance than they are about doubling the capacity of a much slower drive.
Unless you can show conclusive performance versus pricing, with links, I'm afraid I can't agree with the validity of some of the information shown here.