I just installed a new pair of marathon pluses last night. While my forks/fenders had plenty of clearance, it was a chore getting 32mm marathons onto a velocity deep V rim. Considering I'd ran 28mm contis before, this additional 4mm seemed negligible on paper. I even popped a tube while pumping to 65psi due to a pinch.
15 miles later they were very comfortable, handled nice and gave me a badly needed traction boost for the wet steep grades in Seattle. I just hope I don't get many flats as my tire/rim combo is very awkward to deal with.