My B4 came with 150/60ZR-17 rear and 110/70zr-17 front Metzler M1s. No idea how they handle in twisties, as my bike died 7 days after I bought it. But overall, the bike seems to handle fine day-to-day; I'm actually wondering if the suspension has been upgraded, because it seems pretty nice (the seller only had it a year and didn't really know much).
I will likely keep using radials, although I wish the rear I have was taller. The 150mm rear certainly looks okay on my bike. The performance advantage of radial over bias ply is too enticing to pass up. They just have a bigger contact patch, which not only helps in cornering but also in stopping the bike. They run cooler, so they seems safer on long rides, and radials can last longer. I also have a ninja 250 which can't fit radials and that is a major drawback of the bike. But this is about riding at the bikes limit, I'm sure bias ply are okay 99% of the time.
Actually, do you have any links handy to articles or forums where they talk about the dangers of using radials on narrow rims?