I think we can afford it and I think it would make the government _smaller_ - it's a complete rework and simplification of social welfare programs and hopefully taxes as well (if done right).
The thing I dislike is that I believe it is what we call a "nice weather" policy in German. It only works as long as the whole system is running, and it will make people forget that people have to work to create all the things we have.
But the biggest pro argument is that I frees people up. Instead of the poor man's struggle for survival, they can live the rich man's live without worries. And thus be in a much better situation to better themselves. Above study seems to indicate the people will indeed try to better themselves, instead of giving up all ambition.