buy a trolley mate to start you off.you can always buy a tank to go with it at a later date!
what gets me about some of the numpties on here they have nt a clue what sort of rounds we have!!ive got 4 different rounds!the 150 very compact estate work would be a nightmare with 100m of hose as there is a lot of parking issues with almost 2 cars per household.the trolley is the better and safer option.
on stand alone properties i use it as a mini-van mount.yes it can be a pain to change barrels but you get used to it!i have the 50L TROLLEY so it lasts me for about an hour before needing changing.a lot of the time i take the trolley out in the morning and put it back in when ive finished around 430pm.
it takes around 50 mins in the evening to fill 300-350L di only into the barrels.also i bring the trolley in every night to charge so it gets protected from frost so no need for van heaters!
i probably will get a van mount in time but ill always need my trolley as well!dont see the point in backpacks really as the capacity is too small!filling up after every house!!now that would be a waste of time!!