July 21, 2018: Just replaced my Michelin Pilot 4 rear tire with the Pilot 5. The last two Pilot 4's have given me 11,175 and 10,569 miles. The 5 seems to have a slightly more aggressive tread pattern. Total cost installed with tax (off the bike) came to $245.
I also have the front tire as a Pilot 4.
One good point on the Pilot 4's is that as they neared the end of their tread life, they allowed normal lean angles. I did not notice that much of an affect on handling which is a great attribute.
I'm starting with 31,387 miles today and I will report back here as I accumulate miles and let you know my thoughts as compared to the Pilot 4's.