van mount all the way for me,
ive got a back pack, which i use for the odd hard to get to job, but couldnt see myself using it all day, it would drive me nuts topping it up all day/ or changing barrels.
i suppose its down to what type of round youve got
eg.. easy access houses = van mount
difficult access houses= b/pack or trolley
combination of the two= van mount and b/pack