Snagging hose and puliing it round obstacles avoiding wheelie bins and plant pots etc is the slowest part, i owuld say the van setup is less important, i.e powered reel or not.
I personally find backpack quicker on a lot of jobs, if you use a bilge pump it can be filled it 20 secs or so. Theres a lot to be said to just lifting up a backpack and pole and away you go.
The easiest way to speed up is finding a solution for each job, mainly the direction you park