Marvelous, with the new package (c720_720-120417-x86_64-1.txz) all my needs for the touch pad on the Acer C720 now seem to be met.Libinput that's included with 720 seems to support the c720's clickpad very well. I've uploaded a new c720 package to the repo (c720_720-120417-x86_64-1.txz). You might want to give that one a go with a clean savefolder. I've also updated the touchpad app in the control panel to work with the c720, that will be in final. The current one in 720beta will work too, but you have to restart X.
Thank you very much kirk !