I'm also trading one of my SB800 for his AiS 180mm f2.8 ED...
I think the 35mm is exactly how Bjorn described it as, internal flare at f1.4 but largely gone at f2 and just really sharp even wide open and peaks at f5.6 or so but who would go that low on such a lens anyway.

The 180mm I only tested briefly but the quality of the photos is quite impressive with it as well, will shoot more with it and get a better idea.