Personally I would go for a bigger van, and system, maybe vivaro/trafic, and a two man 650 litre system.
I would recommend Purefreedom, but heard good things about Grippasystems.
The reason for going for a bigger two man system is , it is better to have it and not need it, rather than buying a small system, and then growing the business, and having to buy bigger.
Plus if you have a two man system, if one part of the system fails, you have a spare to carry on working.
I always try and buy best quality, and in long run saves you lost down time due to system failure
