Had a pair on my RT when the T30 was first released- there was always a bit of a twitch between upright and leaning over, presumably as the different compounds came into play.
They seemed very hard wearing in the middle but the sides wore away very quickly meaning there was a noticeable step in the profile ( a visible step, not just when riding), making the last 1000 miles or so a bit hairy as the transition from upright to leaning over had even more of a hiccup.
I try and stay off motorways so this may have made it worse, they are intended as a touring tyre so the hard wearing middle bit might be useful if you do a lot of long motorway runs..?. I think I got 6000 miles out of them, both wore down equally IIRC.
I think they were revised soon after release-the newer ones might be better.
Switched to Metzeler Z8's- far superior, although they don't seem as hard wearing. I don't do massive mileage so the life of them isn't my main concern.
Never used PR4's so can't compare the two.
HTH