So sent a client around the block on my brand new wheelset Saturday. He had a Giant FSR 3 with stock 700x32c tires which was a $600 bike 3 years back. So inspite of the 700 x50c tires, he couldn't believe how well they rolled and how little effort it took to pedal them. I think 'show me' is lots more effective than any technical discussion.
EDIT: Thing is - the tires and wheelset cost as much as his bike. Which is probably where many clients would balk. In spite of the fact that both the tires and bearings will last 5x as long as the stock ones, the total cost is also 5x as much.
But he was looking for a bike for the GF and has already decided that an $800 bike gives more for the money than a $600 one.