I've never heard anyone say a large float is good for investors, ever!
I play low float tickers -- as a matter of fact that's all I play beside a few OTC's because low float tickers are volatile and better chance of quick returns that couldn't be achieved with a bloated float.
Just as much as there's upside there's downside because of the same reasons, however traders like me that don't mind the risk but still practice good risk management find them attractive, because if there's enough liquidity and the right catalyst then you can make a quick 30 - 50% or more.
Long story short -- it's supply and demand... the smaller the tradable float, the bigger the return and upside, with less hold time.