Lee Seven5 on larger cameras

Has anyone here used Lee's Seven5 filter system on a setup like full frame (i.e. 6D) and a 35mm lens? I haven't been able to find any real information on where the Seven5 filters start to vignette.

I only ask because the starter kit is very attractively priced and I don't really see myself going much wider any time soon. I know it's designed and marketed for the smaller ILCs like the Fujis and micro 4/3 systems.

I changed from the 85mm to the 100mm filter system due to the vignetting at shorter focal lengths. This Lee system is only 75mm - I suspect that you would find it very restricting.