As far as investments, I'm no economist, but I'm skeptical that the money spent purchasing securities has an equal impact as someone buying goods and services locally. It seems like a disproportionate amount would go right back to other members of the investor class, who are going to use it on other securities, or else high-margin luxury items, and very little of that is actually going to escape that bubble.

I think you could argue that replacing benefits with direct income is still a "win" for society. If they're able, it's more efficient for people to meet their own needs than to be provided for through a bureaucratic process with lots of administrative overhead.