Phi really needs to have the ability for Users to customize the Mouse Controls for ROTATE, PAN, ZOOM.
For me specifically, this is my individual Preference:
Middle Mouse Button: ROTATE
Middle Mouse Button + Ctrl: PAN
Middle Scroll Wheel: ZOOM (in and out).
(also, User needs the ability to set the Zoom IN and OUT as they desire).
And what I list above is exactly what I use in Onshape - so it just makes sense to have Phi and Onshape match, making it easier to bounce between the two programs.