I'm using them for their light weight as I use a trolley and a 12ltr sprayer for the odd ones where I don't want to get the trolley out. They run all day on a 7ah battery which is also a lot lighter than the usual 26ah battery fitted to many trollies. The sprayer only has a 3.2ah battery in it wich makes it nice and light (This setup works well for me).
However, if it's for a van I would absolutely go for a Sureflo. They are a solid bit of kit and will probably serve you for 10 years +. (As long as you don't freeze it with water in it)