I recommend following the instructions from the manual rather than those from the mechanic. While he might be a seasoned mechanic, that is not very instructive in terms of his knowledge about the C14, which was brand new in 2008. My OEM tire lasted about 5K miles. The technician changing the tire said the wear patterns pointed to under inflation. So, running with less than the recommended psi might result in a softer ride, but also carries the risk of faster tire wear. I keep 41-42 lbs in my current tires...the front PR2'a have 10K miles with no signs of wear.
To each his own; however, in this case, I am following the manual
I agree. I love all the threads about tires and how few miles people get, then you find out they run the pressure low. I got 8200 miles on the stock Bridgestone front tire on my '09 and 10,000 miles on the rear. Others say theirs were shot at 3,000 miles. I have over 10,000 miles on my Angels at the moment and they don't yet need replaced. On my old RC51 I would sometimes run lower pressure, but only for the track or for fast sport riding through the twisties of Western PA or West Virginia. I live in Western PA and I can get to the edge of my tires 1/4 mile form my house on the RC51. I can do that with stock pressure too. I know that if I lower the pressure there is a tradeoff, I will eat the tire up sooner. On the RC that was okay. On the C14 I want better tire mileage. The C14 is also heavier so I prefer the stock pressure to handle the weight.