and in closing this trhread, a nice new Manfrotto 055xProB arrived today. I'm gonna fun with my 300 F/2.8 now.
For those interested, the Manfrotto 055xProB, 190xProB and 680b monopod ALL fit in the one Manfrotto MBag80P without any trouble. I'm so pleased about this, it makes lugging stuff around just that little bit more tolerable. No heads tho, they fit in my ThinkTank