Hi Rich,
For three years now I've ridden mostly on PR3s, first on my Kaw C-14 and now on my Triumph Trophy, and have been quite happy with them, generally getting around 7K on the rear and 10K on the front (on the Trophy, less on the C-14). On this year's tour, I mounted a set of PR4GTs on my Trophy before starting out. I too had hoped to get significantly better longevity especially on the rear tire, but got only 8,100 on the one rear tire and 8,400 & 9,600 on the two front tires that I had mounted. Since PR4GTs were quite scarce for a while, I had to revert to PR3s on the rear. Although some riders claim to get over 10K front and rear, they are likely to be much lighter than I (@260#) and not carrying much touring luggage, or have a much gentler riding style.
As for handling, I like both PR3 and PR4GT tires, but seem to actually prefer the bike's handling on PR3s. When I have to rely on dealers to supply and mount replacement tires while on tour, the PR3s are also less expensive.
The factory-mounted Pirelli Angel STs on my Trophy also gave me around 7K/10K, but I went to PR3s as soon as possible. I didn't appreciate how the rear tire would look to have sufficient tread depth, but only 200-300 miles later would suddenly show cord along the centerline of the tire, despite still having at least 3/32 of tread depth remaining. I have not tried any Angel GTs.
Don