No one system is perfect, but with a van mount you have to think about your starting point and learn your accounts.
I almost turn into the Hulk at times, the rage I feel when the hose gets snagged or tangled has to be felt to be believed!!!
But by and large I know my troublesome accounts, I think about the obstacles and work out the best way for each account to minimize the problems.
Generally my furthest point is my starting point, pump is turned on before I walk away from the van with hose & pole, flow is off as I only connect the pole hose to the microbore hose once I'm at the first window.
With 100m of microbore that gives me a potential span of ten houses - 5 one side, 5 the other - that's if they are all next door to each other of course.
At some point I may well add a backpack to my toolbox, I think this gives someone with a van mount good versatility, I think you then have the best of both worlds.
I started out with a trolley system and eventually traded up to a full van mount, trolleys are fine, but the downsides are lugging pretty heavy gear around, continually manhandling 25l water barrels, not that heavy I know, but these things are cumulative, and hauling them in and out of the back of a car (most of you will work in this manner) is not good for your back (trust me, ask an osteopath!)
If you have to drag your trolley up or down steps it isn't good!
And time is always lost filling barrels, worrying about running out of water and so on.
Backpacks of course can only carry so much water, the batteries are tiny and most will still have to operate with a load of 25l containers in the back of the car.
Wear them on your back constantly and you are inviting back problems somewhere down the line, plus you are constantly having to take it off and put it back on again, again, not good for the lower back.
So many get a cheap shopping trolley and operate like a mini trolley system.
So you see, all systems have their drawbacks. For those of you that advocate any of the systems I have appeared to diss...you don't need to answer back! The above is done just to highlight the point that you have to keep an open mind, what you use will also depend on the nature of your round.
If you do rows and rows of terraced houses, a van mount will be a real drawback.
Got lots of big work? Large houses/offices and so on? then a backpack or trolley isn't the best option.
And then of course there is the depth of your pocket to consider....
Ian