I use Dunlop GP Racer, 190/55. I've used them on my 2007 R6 too, and have been very pleased with them (and I rode the R6 much harder).
I've been assured that the 190 doesn't allow more lean, but I'm SURE it does.
To me it felt like the 180 was taking a 'square' shape due to the 6" rim, and so the edges had a squarer shoulder rather than nice, round, progressive shoulders.
I found the bike went off the edge and would run around tight/high lean corners on the very edge of the tyre. This caused massive over heating, a tiny contact patch and a loss of stability. It was also impossible to drive out without beginning to stand the bike up.
What I must say though, is this is based on Dunlops. I've been assured that Pirelli 180's have a different profile and suit either 5.5" or 6" rim.