Those were serious questions, mp.
I'm assuming it would be OK to dose less and not have the impressions.
I've tried it and had too many problems with channeling. By using a standard 14 grams and tamping as I do, I seldom have problems anymore.
This applies to my consumer machines without preinfusion. My Bunn ES-1A has preinfusion, plus the pressure ramps up more slowly, so I can underdose without problems.
Everyone has their own way of doing things - this works for me.