I chose the 9-18 over the 7-14 ...

99.9% of the time you never use filters with ultra wide lenses because of vinetting. So filter use on the 9-18 did not matter or make sense to me,

The 7-14 has a constant aperture and thats an advantage to shooting video. variable aperture lenses will automatically change your exposure when you zoom.

The extra coverage the 7-14 is noticeable.

With Panasonic lenses using a Panasonic body is a definite advantage.

If your happy with your purchase of the 9-18 you made the correct choice is all that matters.