Well it depends......
The way that the media is portraying the story is that the benefits recipients are getting that money in their pockets as disposable income. What is actually happening is that unless there are very unusual circumstances (live having a very large number of children) then the people who are in receipt of £350+ get a large proportion of that from housing benefit so it goes straight to their landlord.
As has been pointed out many times in this thread, renting property in South East England in general and in London in particular is very important. While it's feasible to find a 3-bed property to rent in most of the country for £500/month (
here are a few in Newport ), in London it's a different matter. In Tower Hamlets (IIRC London's most deprived borough) it's more like £400 a week for a similar property.