Is SATA bus speed unique for each device despite advertised connection speed?

I'm trying to determine what is the maximum supported SATA version on my laptop. My laptop has: one mSATA SSD, one HD, one Optical Drive.

Using HwInfo, I see:

- BusIntel Panther Point-M PCH - SATA AHCI Controller:

  [SATA Host Controller]
  Interface Speed Supported:    Gen3 6.0 Gbps

So It seems that I have a SATA III controller; but then:

[SATA Port#0] (this should be the HD)
  Port Status:  Device Present, Phy communication established
  Current Interface Speed:  Gen2 3.0 Gbps

[SATA Port#1] (this should be the SSD)
  Port Status:  Device Present, Phy communication established
  Current Interface Speed:  Gen3 6.0 Gbps

[SATA Port#2] (this should be the Optical Drive)
  Port Status:  Device Present, Phy communication established
  Current Interface Speed:  Gen1 1.5 Gbps

So it seems that the HD has a SATA II. In fact under drives the HD shows as:

[General Information]
  Drive Controller: Serial ATA 3Gb/s @ 3Gb/s
  Drive Model:  WDC WD10JPVT-75A1YT0
  Drive Capacity:   953,869 MBytes (1000 GB)
  Drive Capacity [MB]:  953869
  Media Rotation Rate:  5400 RPM
  ATA Major Version Supported:  ATA/ATAPI-5, ATA/ATAPI-6, ATA/ATAPI-7, ATA8-ACS
  ATA Transport Version Supported:  SATA 3.0 

So what's the truth? My best guess is that the laptop has a unique SATA III controller, and the SSD is SATA III so maximum speed, the HD is SATA II so lower speed, the Optical Drive is SATA I so lowest speed.

If I replace the HD with a new SATA III SSD, will it perform as at SATA III or SATA II speed?

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