I can hear the shutter on the old I-40's -- I never had the feeling that it botherd the deer. Those older cameras were great.
I have a few of the I-80's Nice camera, fair battery life, OK trigger speed, good range day/night, good motion area, and very few white outs. I paid about 130 buck for the ones I have and would recommend them. They seem to out perform my Bushnell trophy cams and for less money. Moultrie customer service is not very good.