Well I shaved 100 mm (4 inches) off the pattern at the rear. I was a little too enthusiastic on the first ski. Voile have been very skilled in their design. the grip is only slightly raised above the base at the rear.
the upshot is no noticeable change in grip or glide. Mind you that is only one day of skiing on spring snow with a touch of freeze in the morning. However my conclusion is, that for that type of snow, the 100 mm was superfluous.
I will reserve my judgement until I have tested the skis in different conditions.
It was tricky work sanding off the pattern and getting it smooth. I waxed the base with glide wax and waxed the pattern with a paste wax.