I have mentioned this before, I am on the Q3's and have tried the /55 and /50. I am currently on the /50 series and the difference from the /55 in negligible. I had chicken strips on the /55 and almost nothing on the /50. I think tire profile was the problem with the oem /50 s20s.
That is one thing I really like about the Michelin PR4, 55 rear. I'm not sure I want a tire profile that has no "chicken strip." I corner hard when the opportunity presents on curvy roads, often leaving riding buddies behind. I push the bike at about 80-85%, but always I'm confident that the bike has more left. I like that I still haven't run out of tire.
This is reinforced to me by a sad experience last summer. After several years of using Michelin PRx-series tires on his 2011 N1K, a friend of mine switched to Pirelli Angel GTs. It was a new tire and had good buzz about it. Comparing tires when stopped at a convenience store one day, we noted that his chicken strip was a lot narrower than mine, yet we were riding the same roads. The first day on a trip from St. George, UT to the Flaming Gorge area in late summer (extreme southern Utah to extreme northern Utah), we tired of the severely straight roads and took a detour near Price, UT to find some good mountain roads -- running up Huntington Canyon (SR 31), then down SR 264 past Scofield Reservoir. SR 264 was very tight and technical. And my buddy, with more experience than me, went down (low sided) on a tight, decreasing radius curve. Of course, the bike got busted up bad and he was in the hospital for almost 2 months, requiring titanium strips to be attached to several broken ribs on his left side. "We can rebuild him; we have the technology." It was that severe of a drop, even with full armored gear. He may never ride again.
Similar bikes, similar riding skills, but different tires. Just sayin'...