A number of relevant bug fixes have been committed to the kernel since this driver was backported.  These fixes should probably be backported as well:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=864db9295b06837d11a260e5dacf99a3fdf6bce2
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7229c58c096ca08576cbcbf6669bfbdcae0b5d22
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=23fce365c6a26e40d459ca97289dd18543fb6845
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=47e3a5edc6538d66e470aaed3b7c57255cb37ca1
https://git.kernel.org/pub/scm/linux/kernel/git/dtor/input.git/commit/?h=for-linus&id=e7348396c6d51b57c95c6646c390cd078e038e19
https://git.kernel.org/pub/scm/linux/kernel/git/dtor/input.git/commit/?h=for-linus&id=47e6fb4212d09f325c0847d05985dd3d71553095

I put the following in my xorg.conf to permanently fix the sensitivity issues and disable edge scrolling:
Section "InputClass"
  Identifier    "PointStick"
  MatchIsPointer        "true"
  MatchProduct          "DualPoint Stick"
  MatchDevicePath       "/dev/input/event*"

  # To display current settings:
  # xinput list-props 'AlpsPS/2 ALPS DualPoint Stick'
  # xinput get-feedbacks 'AlpsPS/2 ALPS DualPoint Stick'

  # Scroll wheel emulation is configured by default in
  # /usr/share/X11/xorg.conf.d/11-evdev-trackpoint.conf
  # Default scroll is way too sensitive
  Option        "EmulateWheelInertia"           "80"    # Default 10
  # Middle Button Emulation isn't needed since there is a physical button
  Option        "Emulate3Buttons"               "false" # Default true

  # Use the recommended "polynomial" acceleration profile
  Option        "AccelerationProfile"           "2"     # Default 0 ("classic")
  # Default settings are way too sensitive
  Option        "ConstantDeceleration"          "9"     # Default 1.0
  #Option       "AdaptiveDeceleration"          "1.0"   # Default 1.0
  # The Threshold/Numerator/Denominator set here are usually overridden by the Desktop Manager,
  # so you may also need to adjust these in the Desktop Manager's control panel, or add
  # `xinput set-ptr-feedback 'AlpsPS/2 ALPS DualPoint Stick' 0 7 2` to a startup script run by your
  # Desktop manager.
  Option        "AccelerationThreshold"         "0"     # Default 4 for use with "classic" profile
  Option        "AccelerationNumerator"         "7"     # Default 2
  Option        "AccelerationDenominator"       "2"     # Default 1
  #Option       "VelocityScaling"               "10.0"  # Default 10.0
EndSection

Section "InputClass"
  Identifier    "TouchPad"
  MatchIsTouchpad       "true"
  MatchDevicePath       "/dev/input/event*"

  # To display current settings:
  # xinput list-props 'AlpsPS/2 ALPS DualPoint TouchPad'
  # xinput get-feedbacks 'AlpsPS/2 ALPS DualPoint TouchPad'
  # synclient

  # Use multi-touch button emulation
  Option        "TapButton2"                    "2"     # Default 3 (right click)
  Option        "TapButton3"                    "3"     # Default 0
  # Button emulation isn't needed since there are physical buttons
  # and multi-touch button emulation is easier to use than edge button emulation
  Option        "RTCornerButton"                "0"     # Default 2 (middle click)
  Option        "RBCornerButton"                "0"     # Default 3 (right click)
  Option        "LTCornerButton"                "0"     # Default 0
  Option        "LBCornerButton"                "0"     # Default 0
  # Use multi-touch scroll emulation
  Option        "VertTwoFingerScroll"           "true"  # Default true
  Option        "HorizTwoFingerScroll"          "true"  # Default false
  # Reverse multi-touch scroll direction
  # (Emulate touch screen scroll)
  #Option       "VertScrollDelta"               "-64"   # Default 64
  #Option       "HorizScrollDelta"              "-64"   # Default 64
  # Edge scroll emulation isn't needed since multi-touch scroll emulation is supported
  # (Multi-touch scroll emulation is easier to use than edge scroll emulation)
  Option        "VertEdgeScroll"                "false" # Default true
  Option        "HorizEdgeScroll"               "false" # Default false
  # Disable acceleration in the synaptics driver (use Xorg acceleration instead)
  Option        "MinSpeed"                      "1"     # Default 1
  Option        "MaxSpeed"                      "1"     # Default 1.75

  # Use the recommended "polynomial" acceleration profile
  Option        "AccelerationProfile"           "2"     # Default 1 ("device-dependent")
  # Default settings are a bit too sensitive
  Option        "ConstantDeceleration"          "5"     # Default 2.5
  #Option       "AdaptiveDeceleration"          "1.0"   # Default 1.0
  # The Threshold/Numerator/Denominator set here are usually overridden by the Desktop Manager,
  # so you may also need to adjust these in the Desktop Manager's control panel, or add
  # `xinput set-ptr-feedback 'AlpsPS/2 ALPS DualPoint TouchPad' 0 5 2` to a startup script run by
  # your Desktop manager.
  Option        "AccelerationThreshold"         "0"     # Default 4 for use with "classic" profile
  Option        "AccelerationNumerator"         "5"     # Default 2
  Option        "AccelerationDenominator"       "2"     # Default 1
  #Option       "VelocityScaling"               "12.5"  # Default 12.5
EndSection