I'm jumping into this conversation late, so forgive me if I repeat what another has said. When you say "stronger" and weaker", we need to be sure we know what you're talking about. Are you saying that the Hyroad Pearl rolls stronger through the oil than the IQ Tour Pearl, or are you saying it reacts stronger off the dry? There is a big difference there, and it's something that has baffled bowlers for a long time.
For instance, I used to have both a Virtual Gravity and a Tropical Storm. On my house shot, the Tropical Storm out-hooked the Virtual Gravity. That is to say, when I threw both on the same line and hit the dry, the Tropical exploded at the break point where the Virtual lost power and just kind of slow arced, hitting weakly. At first glance, that would lead some people to believe that the Tropical was a stronger ball. Obviously, that was not the case at all.
The Virtual was ten times stronger than the Tropical. As such, the Virtual burnt energy trying to dig into the oil. By the time it reached the dry, it had very little left. The Tropical, due to its much weaker nature, still had all of its energy stored up, so it made a big move off the dry.
Could this be what you're seeing with the IQ Tour Pearl and Hyroad Pearl? Now, the whole thing confuses me a bit because the IQ Tour Pearl was a clean, strong backend piece for me until I scuffed the surface a bit with 2000 abralon. Still, just based on the covers, cores and such, I would expect the Hyroad to be super clean and super strong off the spot; however, it will probably be pretty allergic to oil, which could by why some people are saying they can only use it during the third game. If there isn't any dry to bounce off of, I don't think you'll see much movement out of the Hyroad Pearl.
Does any of this ring true?