Weizen yeasts and Belgian yeasts produce copious amounts of krausen. Plus I think the viscosity of big beers contributes to more krausen formation.
I don't generally use one, instead I manage by providing appropriate head space.
I have a question though, do you think a blowoff provides any benefits other than preventing messes? Specifically, does it help you get rid of braunhefe that would otherwise fall back and affect beer taste?