These cards can do 6Gbps SAS and 3Gbps SATA, once they are on the latest firmware. When they were originally released they were only compatible with the older standards, so you will see them listed a lot with that product description. HP's own quick specs show the correct info:
https://www.hpe.com/h20195/v2/GetPDF.aspx/c04111623.pdf
I think there were older revisions (possibly with a yellow PCB?) that couldn't be upgraded, but those are rare. There's a lot of discussion on them in the Hard Forum thread posted above.
I can tell you that they work fine, at the highest firmware revision, with all different drives. I have one in a DL370 G6 chassis, using the embedded P410i controller, and it has no problems using a mix of SAS and SATA drives (of different generations, some HP branded and some not). They will work in non-HP systems but I think it's hard if not impossible to flash the firmware without an HP controller card. That said, I've never actually tested performance on them but I've never noticed a problem. My use case isn't too demanding.