Just to add my 2c - the Synaptics behaviour on -current has been much much better since these recent changes; I am not too bothered by the multitouch gestures, although two finger scrolling would be nice. These may work, I haven't tried changing any hw.synaptics sysctls yet. The random jumps towards the bottom-left corner have all but disappeared, for example (these happen under Windows 10 also, using the Microsoft precision touchpad driver, not the original Synaptics one).
I am not aware if we have some support for accelleration. It is a bit annoying, it takes 3-4 full drags on the touchpad to cross the screen diagonally. Anyway, I stopped attaching a mouse to my laptop when I boot into NetBSD.