No, you are wrong. The maximum theoretical bandwidth of PCi-E 2.0 per lane is 4 Gbps. You lose roughly 20 percent of that in overhead.
http://www.xilinx.com/support/documentation/white_papers/wp350.pdf
So the bandwidth deficit is greater than you letting on.
The numbers I used in response to your comments and in the article are accurate, and my statement that "This might cause a bottleneck issue for users if they connect two SSDs to the controller and access them simultaneously, transferring large amounts of data, but it shouldn’t cause a serious problem when accessing drives one at a time or with conventional HDD storage devices." is also accurate. Even your initial comment acknowledged that a PCi-E 2.0 x2 connection cannot run two SATA-III ports at 100% at the same time. I'm sure many users would be displeased with losing roughly 100 MB/s of data throughput when transferring files or using a RAID configuration because of a PCI-E bottleneck, and it was worth mentioning in the article.