I am using a 2013 11' MacBookAir running Ubuntu 16.04 and I am striving to get the Touchpad work as close as possible to MacOSX settings. I am using Synaptics which does a pretty good job, I think. A very bizarre phenomenon, though, is that when I save my settings in the /etc/X11/xorg.conf.d/50-synaptics.conf file and reboot, they are all applied but the three (MinSpeed, MaxSpeed, AccelFactor) affecting cursor speed.
I have modified other parameters (e.g. FingerHigh/FingerLow, MaxTapMove, etc) and they work as they should, namely on startup they coincide with those in my 50-synaptics.conf file although they are not the default values. On the other hand, the three speed parameters keep on remaining the same.
I attach a screenshot of my 50-synaptics.conf file and of a terminal window where I run synclient -l.