I have been using Vade Mecum for about 11 years or so. I have not, as yet, ever had to use all of this software's abilities. What I can say, however, I that I wish I had had Vade Mecum installed on my Palm Pilot when I was a 'working stiff' before retirement. I cannot guess the hours I spent calculating bellows extension exposures with a stubby pencil and a scrap of paper. These days, I check that that my Palm Pilot's batteries are 'full' just as readily as I check that my film holders are loaded.... and my light meter is 'in the bag'.
If Bob's 'Vade Mecum' is 'ported' to the iPhone, I'll be the first customer.