Ah! Yes, you are right! It is so wonky when a controller can only do 6Gbps, but PCI bus is rated for 3.0 speeds. I suppose it will allow the drives to better approach the limit of 6Gbps.
Yup, however, keep in mind it is a natively
16 port card. Adaptec/Microsemi/WhatIsItNow? cannot possibly know what drives you'll connect to it.
If you connected 16x 6gbps SSDs to it...they can certainly do 6gbps sustained
each. Which means you are looking at 96gbps sustained.
And you'll hit the PCIe 3.0 x8 bus limit at that point. 3.0 x8 cannot do 96gbps. (The theoretical bandwidth for PCIe 3.0 is 8gbps per lane, so 8x lanes gives you 64gbps MAX. With protocol/encoding overhead, it's gonna be lower, )
You know all those dual 40gbps cards on 3.0 x8 bus...they can't do full bandwidth either, if you max them out. Will top out at roughly 30gbps sustained at full throttle.